nice idea, going to check it out now
do you have some stats of file sizes before your optimized the images, and after?
ps.. just a few I've uploaded, replacing a file that is 3,31bytes with one that is 247bytes
bravo
PS.. this is a handy tool to compress your images from yahoo
http://www.smushit.com/ysmush.it/
and you can use this test site to see what images can still be compressed
http://www.webpagetest.org