The Steedicons set by Kyle Steed contains 300+ hand drawn icons available as a font or in vector format (.ai, .eps, .csh) for Illustrator, Photoshop, or the wireframing tool of your choice. The bold, sketchy icons would would work perfectly in Balsamiq Mockups or alongside the Konigi Sketch stencils.
Here's a small sample of the icons available in this set.
