Editors

Game Creating Tools

Level Helper
Tiled
Physics Editor
SVG Level Creator
Particle Designer
TNT Animator Studio

Sprite Tools

Sprite Helper
Texture Packer
Spriteloq
Zöe
Glyph Designer

Graphics Editor

Pixen
Graphics Gale
Pixelmator
Adobe Photshop
Adobe Fireworks
Axialis Icon Workshop
Inkscape
Adobe Illustrator
Gimp
Paint .Net

Text Editors

Notepad ++
TextEdit
BBEdit
TextWrangler
SublimeText
Fraise
Smultron
Kode
Vim
IndeEd