Check out these Earbuds Volume headphones ($16) sold at the MOMA store. Each earbud is designed to look like a traditional volume knob.
These aren't my favorite quirky earbuds (that honor goes to the animal earbuds I spotted a few months ago), but their design makes them doubly geeky. They're compatible with any MP3 player or headphone-enabled device. What do you think? Too geeky for your taste? Or do you think they're cute?