I was reminded of this by a post from Tirian in the gaming forum.
We don't have many web designers or application developers here, but if you know someone who might be into that sort of thing, tell them to take a look at Yusuke Kamiyamane's work. He designs icon sets that are widely used in the open source world and elsewhere. You can use the icons free of charge so long as you provide attribution somewhere in the application (Creative Commons Attribution something or other), but you can also buy royalty free icons for $60. While that might sound like a lot, you are purchasing the rights to use the icons in his Fugue Icon Set (literally thousands of icons) without having to provide the attribution. Plus, a portion of the purchase is donated to a disaster relief charity of Mr. Kamiyamane's choosing.
I bought a set since I've used them on a few projects, but not so much for the royalty free license. I don't mind providing attribution for great work, but the fact that I've used the icon sets in so many places and that part of the proceeds are being donated, I see nothing wrong!
If you know of any other designers or developers who are or have been looking for an icon set, send them a link to his site. $60 for hundreds of icons is actually pretty cheap when you consider that most stock photography for a single photo can go in upwards of $20--and we're talking low resolution!
Edit: Corrected icon counts. The Fugue set has 3,000 icons both with and without shadows in addition to a few hundred bonus icons.