Music
Spoiler
Cell7
Great list of modules collected by Tapeworm, the creator of Seiklus.
http://autofish.net/cell7/music.html
ModPlug Tracker
Great program for making modules and other music types
http://openmpt.org/features
ModPlug Player
Plays modules.
http://openmpt.org/legacy_software
SoundImage
Original, royalty-free music.
http://soundimage.org/
Melody Generator
Online MIDI generator.
http://www.nici.kun....lody/index.html
aria ENGINE - Free SFZ Sounds
Various free soundfonts.
http://ariaengine.com/free-sfz-sounds/
3.5 GB Of HQ Ochestral SF2
Excellent orchestra soundfonts.
http://www.newground...s/topic/1200140
(
http://www.newground...s/topic/1162814 500 MB more)
PatchArena - Free SFZ Instruments
Collection of free soundfonts.
http://patcharena.co...fz-instruments/
Sonatina Symphonic Orchestra
Really good free orchestra sound fonts - nearly an entire orchestra.
http://sso.mattiaswestlund.net
Hammersound
Collection of soundfonts of variable quality.
http://hammersound.net
The Mod Archive
A very large music module collection with a public domain section.
http://modarchive.org/
131 module pack by RekNepZ collected from The Mod Archive (make sure to find credit details on the site for ones you use)
https://www.dropbox....odpack.zip?dl=0
MuseScore
Free music composition and notation.
http://musescore.org/
SolMiRe
Convert a MIDI to MP3, can use your choice of soundfont.
http://solmire.com/
GXSCC (Beta version)
Convert a MIDI file to a WAV file using actual 16-bit instruments. Can be used for commercial projects.
http://www.geocities...B236/indexE.htm
MP3Cut
Upload an MP3 file and cut it to whatever length you want.
http://mp3cut.net/
Abundant Music
A very easy-to-use online music generator.
http://www.abundant-music.com/
Soundation
A free online music creator.
http://www.soundation.com
TeknoAXE
Royalty Free Techno, Dubstep, Metal, Rock or Soundtrack music.
http://www.teknoaxe.com/
LMMS
A free open-source music making package. Originally made for Linux systems, but ported to Windows.
http://lmms.sourceforge.net/
Tunafish
Another, older yet simpler music making application
http://www.brotherso...fish-88125.html
KVR Audio
More music stuff (VST, VSTi, and more)
KVR Audio
Akoff Music Composer
A funny little application that converts wave to MIDI. You can make music by simply humming into a microphone
http://www.akoff.com/index.html
FamiTracker
Nice 8-bit music tracker
http://famitracker.com/
cgMusic
MIDI music generator using editable algorithms
Note: May or may not work on a 64-bit system.
http://codeminion.co...s-create-music/
Wolfram: Tones
Procedural mathematical music generator
Wolfram:Tones
FreePD
Resource for public domain music
FreePD
Anvil Studio
Well-known general-purpose MIDI tracker
http://www.anvilstudio.com/
SynthFont
An application good for putting "finishing touches" on your MIDI files, like soundfonts and VST effects
http://www.synthfont.com/
IndieGameMusic
Here, you can request music from composers
http://igmusic.us.to/
FL Studio
Another popular tool for making music
FL Studio
Sound FX
Spoiler
sfxr
Waveform sound effect creator
http://www.drpetter....oject_sfxr.html
as3sfxr
A custom build of sfxr; works in browser!
http://www.superflashbros.net/as3sfxr/
bfxr
Another custom build of sfxr.
http://www.bfxr.net/
LabChirp
8-Channel sound effect creator with randomizer option
http://labbed.net/so...php?id=labchirp
Audacity
All-purpose sound editor
Audacity
Curvesounds by Greenblizzard
A sound creator that allows for hand drawing the frequencies.
http://gmc.yoyogames...howtopic=582263
Supersound by tsg1zzn
A sound extension that provides .ogg features and more to GM8.1 users and below.
DLL:
http://gmc.yoyogames...howtopic=120034
GEX:
http://gmc.yoyogames...howtopic=462692
Graphics
Spoiler
Sparks by Nocturne
Generates effect sprites using particles. Can also generate particle code.
http://gmc.yoyogames...howtopic=539511
SkyGen by GVmakesGames
Procedural day/night sky background generator.
http://gmc.yoyogames...howtopic=662933
Blender
Free and popular 3D modeling and rendering tool.
http://www.blender.org/
Spritely
Placeholder image generator; pulls image from the internet for placeholder sprites.
https://github.com/g...gelina/spritely
Spriter
Popular spriting and animation program.
http://www.brashmonkey.com/spriter.htm
Procedural Trees by TheSnidr
Another tree generator, but creates scary-looking trees. Open source!
http://host-a.net/u/...dural_trees.gmz
Pixlr
A free online image editor.
http://pixlr.com/
CanTree Tree Generator
A very good-looking 2D tree generator. Very detailed trees of any size can be made.
http://arnaud.ile.nc/cantree/
Particle System Creator by Mercerenies
A GM-made what-you-see-is-what-you-get particle creator that creates code for particle effects.
http://www.sandbox.y...-system-creator
Open Game Art
A resource for general graphics
OpenGameArt.org
CG Textures
A huge collection of textures of all kinds
Note: You must register to download textures. It's free for small textures, but you have to pay for larger sizes.
http://cgtextures.com/
Explosion Texture Generator
A very nice-looking explosion graphic generator
http://www.saschawil...de/?page_id=253
Lost Garden: free game graphics
This site has some amazing looking free game art. Scroll down this page to see them.
http://www.lostgarde...e game graphics
Bleed's graphic collection
A collection of nice pre-rendered 3D graphics by the GMC Member, Bleed.
http://gmc.yoyogames...howtopic=460652
GIMP
Powerful free image editor.
GIMP
IcoFX
Tool for converting images to icons that can be used in GM games
IcoFX
Model Processor by TheSnidr
A tool for importing textured .obj models, outlining them, then exporting gml models.
https://host-a.net/u...l_processor.exe
GML Color Picker by seanrr
Easily get the colors you want for drawing things
GML Color Picker
Icon Maker by Big J
A good icon maker for making icons for your GM games
Icon Maker
Spriter
A popular sprite editor, allows you to easily animate sprites and add collision systems and stuff
Use this to add Spriter graphics to your game:
http://gmc.yoyogames...howtopic=537492
Spriter
iconverticons.com
An online icon convertor
http://iconverticons.com/online/
The Spriters Resource
A HUGE database of sprites and graphics. You probably shouldn't use them in your Jam game to much because of copyright stuff, but you can use them as bases and references for making your own sprites.
http://www.spriters-resource.com/
Fontstruct
A vector-based online font editor, that also has a gallery of fonts other people have made.
http://fontstruct.com
BitFontMaker2
A font editor that makes pixelated fonts using a simple paint interface.
http://www.pentacom..../bitfontmaker2/
BitFontReader by YellowAfterlife
Simplifies the process of making pixel fonts.
http://yal.cc/r/bitfontreader/
Planning & Ideas
Spoiler
Random Idea Generator by Koder007
A browser-based random game idea generator.
http://codepen.io/Koder007/full/iblAf
The Random Game Idea Generator by Kepons
A somewhat hilarious game idea generator.
http://gmc.yoyogames...howtopic=597853
Random Horror Plot Generator by GVmakesGames
A configurable plot generator. It's pre-configured for horror plots, but can be changed to other genres.
https://gvmakesgames...plot-generator/
Seventh Sanctum
A huge collection of generators for many things such as names and plots
SeventhSanctum
Idea Creator by trg601
An html5 app that generates a random idea for a game
http://tyler.co.nf/files/ideagentool/
IdeaGM by N-cubo
Another browser-based game idea generator with over 107000 possible combinations
http://ideagm.n-cubo.com/
Extensions (GML, DLL, GEX)
Spoiler
GMLScripts
A great resource for all kinds of scripts
GMLScripts.com
GM ToolBox
A great collection of DLLs and extension packages
GM ToolBox
Mike Deroche's DLLs
Some good DLLs here
http://mikederoche.com/resources/dlls/
Blijbol
This GM-oriented site has a nice extensions section
http://gamemaker.blijbol.nl/en
Supersound by tsg1zzn
A sound extension that provides .ogg features and more to GM8.1 users and below.
DLL:
http://gmc.yoyogames...howtopic=120034
GEX:
http://gmc.yoyogames...howtopic=462692
Engines and custom IDEs
Spoiler
NaturalGM
Custom editor fo GM:Studio; has a nice, clean interface
NaturalGM
VEditor
Custom level/room editor
VEditor
Code generating editors
Spoiler
Particle System Generator by Mercerenies
A GM-made what-you-see-is-what-you-get particle creator that creates code for particle effects.
http://sandbox.yoyog...-system-creator
Bullet Pattern Studio by darkwalker247
A GM-made bullet pattern creator that contains many features that allow for complicared pre-planned bullet patterns.
http://gmc.yoyogames...howtopic=570806
Other
Spoiler
Convertico
Another tool to convert to ICO
http://convertico.com/
Extra Credits
A "series on how to design games well, telling you what to avoid and tackling difficult subjects in gaming".
https://www.youtube....9B0CA00461BB187
Open Broadcaster Software
Useful for making let's plays for Jam reviews, or live streams.
https://obsproject.com/
Chronolapse
A tool for easily creating a time lapse video of your game's creation.
https://code.google..../downloads/list
The Open Bundle
An open bundle of music, and art from web games. Available under the Creative Commons Zero license.
http://open.commonly.cc/
What The Font?
A pretty cool online application that extracts font types and styles from images with text in them by matching against a database. For example, it can be used to replicare the fonts used in text on sprites.
http://www.myfonts.com/WhatTheFont/
Zamzar.com
An online converter that converts almost anything to other formats. (For example, PNG to ICO, MP3 to WAV, FLAC to MP3)
http://www.zamzar.com/