Smushit reduces the file size of images by reducing the number of colors, strips off excess metadata, and also discards other non visual data.
There are three ways you can use Smushit:
- Upload a bunch of pictures in your browser
- Provide a list of image URLs
- Firefox Extension to optimize the images found on any web page.
Interestingly, the Smushit site seems to hosted on Dreamhost, not on Yahoo servers as one would expect. Thanks Webware.