Audio-Technica AT2020USB+ Cardioid Condenser ($149)
The AT2020USB+ is our favorite all-around microphone for video-conferencing that does a great job at picking up your voice, without too much sensitivity for background noise (helpful if you're living with other people!).
Blue Snowball USB Microphone ($49)
The Snowball is a tried and true microphone that's been around for awhile. The stand makes it portable and easy to prop up near your face.