Free Social Media Icon Set from Visual SwirlPosted on February 11, 2010 and got 2 shouts so far
Visual Swirl give us social media icon set named Green Thumb, these icons are vector-based in four different sizes (256×256, 128×128, 64×64 and 32×32 pixels). Green Thumb contains some social media icons in greeny-style including Delicious, Facebook, Stumbleupon, Twitter etc.
The author allow us to use these icons for any purpose without any restrictions except for resold, sub-licensed, rented, etc. You can download and view these icons example here.