Ask TUAW: What's Your Best Source for Icons and Desktop Pictures

Now that you've had your Mac for awhile, you've started to figure out how to customize its interface to suit your tastes. Simple question, what's your best source for icons and desktop pictures for your Mac? Free is great, but shareware is acceptable also.

My two favorite places for icons--but certainly not the only ones--are InterfaceLIFT (formerly Xicons) and IconFactory. For desktop pictures, my favorite place is Astronomy Picture of the Day.