I love free concerts. Especially if the group(s) are in vein of my interests. Part of the reason I love the DC area, all the free stuff that goes on in and around a major metropolis city.
I recently had the pleasure of seeing The Lovell Sisters at a venue just outside of DC, free of charge (their MySpace page).
Quite frankly, I was highly impressed by their music and voices coming from 3 people so young! They play a blend of Folk Rock, Acoustic, and Country.
Here's a little YouTube.com video that shows how good these three girls are: