For one of my recent projects I looked for simple icons, that are free to use. Well, to put it in a nutshell, I didn’t find, what I was looking for. So I fired up Inkscape and created a set that fits my need. Here it is, simple, plain, monochrome and free to use (a.k.a. in public domain).
The PNG was created from this SVG image, which I’d like to suggest you for further processing. Each icon’s SVG representation is as simple as possible, mostly a short path element. The icons are designed to be used at 24×24 px.