They are absolutely free, they look great, and there are literally thousands of them. I counted them and came up with 4,400.
Did I mention they're free? Not only that, Paul also said he would be open to creating any missing icons you may need on-demand. Just post a message if you can't find something, and he'll try his best.
This, ladies and gentlemen, is impressive.
and 6 more sets...
The downloads are waiting for you at Tehkseven.