I mentioned The Struts. They've been on the late night shows and were sort of the anchor act for the Victoria Secret Fashion show recently. So hardly unknown and they've been touring for 4 years. Still, a lot of folks here probably haven't heard of them.
One of my favorite and much lesser known acts is the Teskey Brothers. Heard of them here on Audiogon. If you like R&B in the vein of Otis Redding, Wilson Pickett, etc, you'll like these white kids from Australia. Good stuff. I emailed their agent a few weeks ago and they will be touring the US this summer.