You can find the tool here: http://aseprite.org/
I've used it for months and I've never ran into any problems with it. It's very simple spriting and onion-skinning, so you can see what your previous frames were. It also supports indexed palettes, so if you can alter the palettes of sprites and limit the colors!
@Dragon - Thanks, mate. If it's an easy to use animating tool, I'm game. I've been stuck making these frames because it's been hard figuring out the movement without the actual animation.
Very nice! You managed to instill a lot of character into a small amount of space, and I'll say that I like the glasses! Something I don't see a lot on small sprites.
Ohhhhhh animation, you say? Why not try making some .GIFs in ASEprite? It's a fantastic program I use to make my animations! And if you know how to use MS Paint, it shouldn't be that hard of a program to use.
Nice. Very like it. Good solid character.