She's a singing actress actually and has been working currently at Broadway. Here's her bio:

link

If i were u, i would go over youtube, type her name (Jaime lee Kirchner) and see what comes up.

Thanks!

Oops! :O Although Jamie Lee Kirchner is a singer, it looks like the songs performed in "stage fright" are not hers. They're Kimberly Cole's and here you can hear them out again:

link

Yeah, ditto to movygirl! The songs were written and sung by Kimberley Cole and when she agreed to have them in Dollhouse, Joss gave her a role as one of the backing singers alongside Eliza =)