IcoMoon

This will be super useful for my next website designs. Thanks a lot, @erictwillis you really are THE product hunter.

"IcoMoon is striving to build and provide the best iconography and icon management tool for perfectionists. IcoMoon's icon library features only the very best icon sets out there. All of our icons are designed on a precise pixel grid. The IcoMoon app lets you build and use your own icon sets in different formats including SVG, icon font or simple PNG/CSS sprites."

I've been using this to make custom icon fonts for the past year or so. Incredibly easy to use and the SVG import stuff really puts it over the top.