PremiumPixels has always provided awesome packs of icons or themes, and recently they did it again. They published a nice set of mono-colored icons that you can use in your project.
The name of the pack is Pixicus and has 106 pixel-perfect mono-colored icons. Icons consist in like actions, social networks, users or devices and they come in transparent PNG format having 12*12px sizes.
106 mono-colored pixel-perfect icons – Preview