Thank God for the open source community and those people who are willing to give up their time to produce top quality goods for us all to share. In this post I have a whole bunch of top quality free (as in read the license before you use them) icon sets for your personal and commercial sites.
Why is important to have a post that provides icons for commercial use? Besides being handy to have your own pool of quality icons that you can use on any site, many developers start out working on small commercial projects and it's hard to come across a range of good quality icons. Sets such as FAMFAMFAM pop up all over the web and it was the first free icon set I ever worked with and it's still used in many projects today.
I don't want to provide you with links to sites with hundreds of sets where you have to wade through to find anything decent and I don't want to provide you with "80 free icon sets for commercial and personal use" where most of the sets only have 5 icons or only two out of eighty sets can be used in commrecial projects. Folks, this is the good stuff; five sets of icons with no less than 100 icons in each.
In order to share the love, I have provided a link to the actual site where the icons reside not just a direct download link. These people have taken there time to design some top quality icons for us all to use so take the time to have a look around while you are there.
Note: licenses change, please read (and obey) the license of each set at the time of download