The chick who does it is an actress. She is one of the Best Buy people in Blue, she has been on house and she has also been on one of the best web shows ever, Dr Horribles sing along blog.

http://www.hulu.com/watch/28343/dr-horribles-sing-along-blog

Her name is Felicia Day - http://www.imdb.com/name/nm1260407/