Hello,
I'd like to present my new online tool for web designers.
It shrinks PNG-24 files to PNG-8.
compresspng.com [we'll leave the URL on here, but not the active hot-link - wdf staff]
As far as I know it's the most effective PNG compressor available online. I compared its results with competitors (tinypng.org, for example). In my tests it ALWAYS produces smaller files, with exactly the same quality.
But the main difference from other online tools is the ability to reduce the number of colors far below 256.
I found that for most of my interface-related graphics 8-32 colors is quite enough. That gives me 4-5 times smaller files than PNG-24, and 1.5-2 smaller files, than 256-color PNG-8, generated by other online tools.
Please let me know what you think.