Tools:
Engines:
Game Maker – wiki available here
Python w/ Pygame
Unity game engine
Angel – created for EA game
jams
Scirra
Love – 2D game engine
XNA with Visual Studio C#
Environments:
Scratch http://scratch.mit.edu/
Greenfoot http://www.greenfoot.org/about/
Art:
Spritelib
Sprite Walk Cycle tutorial
http://www.manningkrull.com/pixel_art/tutorials/walking.asp
GIMP
Sumo Paint
Inkscape
Lost Garden
Graphics
Frogames [Dungeon Pack]
Paint.net
Google Sketchup
Wings 3D
Blender