I currently have two registrars as my "main" registrars (Namecheap and DirectNIC) with a couple of others for one-off names. I'll eventually transfer them into one of my main registrars. So I'll say 2 for the poll.

What about the rest of you?

Well, I have three (3). My main is Stargate though. I have domains at godaddy as well. And I have a .info domain in another registrar.

Reasons: Just need to test out control panels. Another reason is that one registrar does not have the domain extension available.