Zalman and Antlion are decent clip ons that I've seen recommended.

http://www.amazon.com/Zalman-Zm-Mic1-Sensitiv...rds=zalman

here's a link to the antlion mic, there's a new one coming out soon:
http://modmic.com/

I have one and they're great.

the one zoot uses

Bump

stolen from other thread:

there you can listen to the sooundquality of the zalman: http://youtu.be/M78z6l_GFao?t=6m31s

I'm not as much interested in the quality of the sound, but more to how much background noise it picks up. It doesn't need to record my keyboard and mouse clicks and the PC humming in the background.

Yeah I could care less about the sound quality. As long as it doesn't pick up everything in the room I'll be happy.

To avoid background noise you'd want a mic with a cardioid pickup pattern aimed somewhere at your general direction and away from the general direction of your input devices. Obviously it would be nice if you could position it relatively close to the source of sound you want to capture (you, that is), and as far as possible from the other sound sources.

edit: I doubt if any of these clip mics are cardioid, but if they work well isolating any clicks and claks, then cool.