Make PNGs Not Suck

Mac users, read The Sad Story of PNG Gamma, and then download GammaSlamma.

In short, PNG is a potentially useful file format hampered by a well-intentioned but disasterous attempt at simple color management. But when you remove the bogus Gamma flag from a PNG file, you've got an elegant and free cross-platform lossless image format.

Windows users can aparently strip out PNG Gamma flags with PNGCRUSH.

I've tested neither of these, so please let me know if they work for you!