[Codein]

I've heard iDraw is a good one amongst pixel artists but I myself use Adobe Photoshop. I don't think it's a matter of program really just as long as you have a pencil and colour selector. I only use Photoshop for pixel work because it's the program I'm most accustomed to. Don't listen to people telling you to buy Photoshop because, for what you're wanting to do, iDraw suffices.