Finding free fonts on the net isn't really all that hard - the list of sites offering gratis typefaces is a pretty one. Good quality fonts? That's a slightly shorter list.
Good quality free fonts that can be used commercially? That list is even smaller.
Thankfully, the good folks behind Font Squirrel have worked their tails off putting together a large collection (currently 338) hand-selected typefaces that may be used in all your projects, both personal and professional.
Fonts are broken down into the usual families like hand-drawn, grunge, serif, and typewriter. There's a search box as well, helpful for quickly checking whether or not the Squirrel has a specific font.
I was pleased to find Mirisch, one of my favorite Ren and Stimpy-esque fonts.
Font Squirrel offers 300+ quality, free, commercial-friendly fonts