Freebbble!

Available as Webfont, PDF, Adobe Illustrator, PSD, PNG (original and 512×512 size) and SVG file.

Linecons – 48 outline icons is a free Icon design resource made by Dribbble user Sergey Shmidt. As far as I can tell, its license is Free for Commercial and Personal Purposes.

Helpful hint: Dribbble users are nice. If the license is unknown, it is usually because they forgot to mention it explicitly; not because they were being stingy. Ask nicely and they will probably allow you to use it.