Useful for experienced devs looking for new tools or beginners who are still learning, the resources sheet by Global Game Jam is essential (click here to view). 3D modelling programs, drawing or even game engines available.
Another never-ending fountain of knowledge is the Pixel Prospector website, which also includes other topics convering the game publication thing (like marketing and business models). Not important for the game jam, but perhaps useful later (read it here).
Visual Programming Language: Gamesonomy
The easiest way to make a game for beginners is most probably Gamesonomy, a visual programming language that allows you to create your own games on the cloud, using a really simple graphic interface. In this case, Gamesonomy has available a lot of different video tutorials. Please take a look!
One of the most common recommendations when a new game dev starts creating is this: clone classic games before you go for something more difficult! Let’s start with that then. Find here the first part that explains how to create a Pong clone with Gamesonomy (video in Spanish).
Assets: Music/Sound/Graphics (2D/3D art)
Last but not least, a great help in those cases where you don’t have time or partners to create graphics or sounds, again available thanks to the Global Game Jam crew.
Everything – http://opengameart.org – most models in Blender format
3D Models – http://turboSquid.com http://www.blendswap.com/
3D Models, Textures – https://www.assetstore.unity3d.com
Textures – http://www.cgtextures.com
Textures – http://www.openfootage.net
2D sprites and Flash backgrounds – http://glitchthegame.com/public-domain-game-art/
2D art list – http://bit.ly/18avkmQ
Music (and graph paper!!) – http://incompetech.com
Music – http://www.newgrounds.com/audio
Sound Effects – http://freesfx.co.uk
Sound Effects – http://soundbible.com
Sound Effects – http://freesound.org/
The Open Bundle (Music, 2D assets) – http://open.commonly.cc/
Fonts – http://www.1001freefonts.com
Fonts – http://www.fontriver.com
Fonts – http://www.1001fonts.com
Fonts – http://www.fontsquirrel.com
Fonts – http://www.iconian.com