Let's see ....
Lama Sarah Harding - http://en.wikipedia.org/wiki/Sarah_Harding,_Lama
. I know Lama Sarah personally and she's a great teacher. She's taught at Naropa since '92 and translates Tibetan texts. She also leads a small community of Green Tara practitioners.
Lama Palden Drolma - http://www.lamapalden.com/
I've havn't heard her teach, but will on Saturday as a part of Ponlop Rinpoche's Rebel Buddha Tour stop in Boulder this weekend. I have several friends who have heard her teach and they think very highly of Lama-la. I'm looking forward to seeing her.
Theres also Lama Tsultrim Allione (http://en.wikipedia.org/wiki/Tsultrim_Allione
) who founded the Tara Mandala center near Pagosa Springs, CO and is thought to be an emanation of Machig Labdron. Although I've never heard her teach, she's well respected in Colorado Buddhist circles and has a sizeable following.
And last but not least, there's Lama Cathy Wesley - http://www.lamakathy.net/