Icons allow web designers to add extra finishing touches to designs, icons can help convey important messages or call to actions to the user in a stylish and unobtrusive way. Icons can help add to the overall user experience  without using excessive amounts of text which can clutter the web page. I keep a good selection of both free and paid icons on my Macbook which I am always adding to as I find new released icons. Here a some of favorite free icons for you to download and add to your collection.

Picons Social

Tiny Icons

Mac OS X Lion Icons

iconSweets

Jonno Riekwel

Iconic

Token

Default Icon

Free Vector Icons

Glyphish

Your Neighbours

Marker-Style Icons

Devine Icons

Drinking Icons

Pro Glyph Iconset

Devine Icons

128 x 16 x 16 Icon Set