I would bet that every person reading this has been exposed to the work of Mark James. If you have used any web based application you are likely to have seen his Silk icon set. Not only are these very well designed icons, but they are actually free to use. I have used them myself in Klok and many other applications I have worked on.
As I download and try out many of the apps entered in the AIR Developer Derby I can't help but notice them used all over the place. On behalf of all the developers, and designers, who don't have the time or skill to create our own icons... Thanks.