- FlashDevelop(IDE)
- Flixel(game engine/library) and the Flixel Power Tools
- Ogmo Editor(a tile-map level editor)
- The Gimp(I use it for pixel-graphics but it's a general purpose image editor)
- BFXR(sounds effects generator)
Wolfram Tonesinudge(music generator)
What do you use for rapid game making?
-Ido.
EDIT:
- Tip from ratking: inudge (another music generator)
- Tips from deskwater: OpenGameArt and OpenClipArt