Alex Peattie: JustVector Social Icons
150 monochrome social icon vectors.
Linecons Free
48 line-art icon vectors.
Foundation Icon Fonts
A freshly updated icon font set that you can use with CSS on your next Foundation project.
Entypo
250+ pictogram vectors.
Minicons
200+ icon vectors.
Streamline: 100 Free iOS7 Vector Icons
100 vector icons that resemble iOS line-drawing icons.