This Perl extension aims to cut down the size of PNGs. Users pass a PNG to
various functions (though only one presently exists -
Image::Pngslimmer::discard_noncritical($blob)) and a slimmer version is
returned. Image::Pngslimmer is designed for use where PNGs are being
generated on the fly and where size matters - eg for J2ME use. There are
other options - probably better ones - for handling static PNGs.
and more image types.

WWW: http://search.cpan.org/dist/Image-Pngslimmer/