Including a $65 royalty-free icon kit.

Best icons ever. I need to adopt these somewhere. Anywhere!

The list below represents some amazing work by various artists who have made their work available to the general public for a variety of uses. These icons are all free.

From Nonstopmac.com. Good selection of links to wallpaper, icon, and other resource sites.

An attempt to make a single cross-platform UI experience for OSS. Includes a base set of icons, icon naming specs, and so on.

I could really have done without the little pixelated naked Mario.

Pixen2: Pushing pixels to the limit. A pixel-oriented drawing tool. At first glance the interface kind of reminds me of Seashore.