No, I don't think you should get any tank mates. No matter how good the filter is, there just isn't very much overall space. It would most likely end up in either your betta or the tankmate being badly beaten up and possibly dying as a result. A 2 gallon is really only adequate for your betta.
I'm not even gutsy enough to put anything into my filtered 5 gallon tank with the single betta that is in there for exactly the same reasons.
Last edited by Eolith; 01-01-2010 at 10:58 AM.