Free PNG compression with punypng
Make sure you try punypng, a free PNG compression service that drastically reduces images file sizes.
I uploaded both a true color and an indexed color version of the same image, and while the indexed version’s file size was reduced with 13%, from 2,720 to 2,388 bytes that is, the size of the true color file was reduced with 41%, ending up a mere 2,385 bytes (coming from 4,017) which happens to be even smaller than the version that was originally smaller to start with!