I've been working on several projects with a couple of former colleagues (Stuart Colville & Cyril Doussin) and we've just released the first of these - a favicon generator. The CSS Sprite Generator tool we released back in 2007 has also had a new lick of paint and we've set up Project Fondue to promote our work so check back often for new tools.
Here's an extract from the about page text from the Favicon Generator which explains exactly what it does.
This tool provides an easy way to convert any GIF, PNG or JPEG to ICO which is supported by all modern web browsers. It also enables you to create favicons from scratch via a handy online editor. Additionally the editor lets you manually tweak generated favicons to ensure the best possible result.