I recently discovered the band Zephyr.
They are from Boulder of Colorado, the place a majority of the hippies eventually landed. I've only heard tales of Boulder - it sounds like it's still the 60's there.
Zephyr only released three albums from what I can tell. Their first two albums featured Tommy Bolin of Deep Purple fame. He's the guy who came after Ritchie Blackmore. So you know there's some really good guitar in this band.
They are fronted by a female named Candie Givens. She sounds as good as Grace Slick and Janis Joplin.
I'm surprised I hadn't heard of this band earlier. They sound as good as what I've heard from Jefferson Airplane, if not better. Their jamming seems way better, and I mean why shouldn't it; their guitarist was good enough to replace Ritchie Blackmore. Just good old classic late 60's sound, although they were an early 70's band. I don't think there is a better era for rock.
Read more about the band here: http://Last.fm.