Free set of forms, icons, styles, etc for web-based admin interfaces

Question

Is there any free set of forms, icons, styles, images, etc for building web-based admin interfaces? If yes, which is the best?

Answer 1

Tango icons is a set of free-as-in-speech icons. It is covered under CC Attribution Share Alike 2.5 license, so it should be viable for commercial work.

Answer 2

Icon Archive

is one of the very best source for any kind of icons.

Answer 3

http://www.iconspedia.com/

Answer 4

A particularly common choice is Silk. It's a very comprehensive free set. There's also the Silk Companion 1.