Piskel is a free online tool to make pixel art and animated sprites for your game. As well as seeing a live preview of your animations in browser, you can also browse and remix other's work, so you can see how other animations are made. You can also easily export your work to GIF or PNG file formats, making them easy to import into your game engine of choice.

• Check out this tutorial video on Piskel by TodaysTuts
• Get the tool here.