Creating sprites for 2D games can be a very time consuming process.
After becoming so smitten with Inkscape for vector graphics it occurred to me that one could use vector graphic animation to generate sprites. I've not used it, but Synfig is a free / open source 2D vector animation package.
After creating a vector graphic character, you can build an animation quickly from a few key frames, rather than animating every frame at, say, 30 frames per second. You can then quickly export the animation to bitmaps, and plug it in (likely using some other tools for image manipulation). Finally, you can quickly modify the animation and re-export it without the need to manually touch thousands of pixels.