What's a good tool to use for making pixel art for games?

[Spenner]

Photoshop is what I'd recommend. Using the timeline/animation panel would be particularly handy if they are animated sprites. The ability to export different formats may help if you are doing something flash based (I forget if flash still attempts to vectorize/posterize pixel art when it is pasted in, or perhaps thats just an option I hadn't ever turned off)

2nd choice would be GameMaker lol. Mostly because nostalgia goggles for me, but I've had fun building animated sprites pixel by pixel before. They always turn out very clean, as opposed to doing things that fuzz details (rotating small pixel art in photoshop may compress the art in a way you do not like. Not that it's not fixable... just standing up for gamemaker :'] )