Free Simple Icons.
This icon set was originally created by Amit Jakhu for his personal use. It’s very generous of him that he now releases the complete set for free download without any restrictions on usage. All icons are designed in a nice simple style. The icon set includes PSD, AI, PDF, EPS, SVG, and webfont versions. The shown icons are only a small selection of the entire set. If you want to see more, check out here.