FamFamFam Silk Icons
An almost impossibly comprehensive and well executed collection of more than 1000 16x16px icons by Mark James.
The 'Silk' icon collection is a fantastic resource for all web designers and programmers.
And rather than milking it for all it is worth, James has chosen to release the whole collection for everyone to use free of charge under a Creative Commons Attribution 2.5 licence.
What more could you possibly want?
» www.famfamfam.com