Maggi: there are others, I think if you do a search under Boston B & B's, many will come up - including the Newbury St Guest House which gets good reviews, although personally I have never stayed there - and also a very popular one in Somerville which is a T stop or so out of town- if I can find that thread I will link it here or top if for you

http://www.morrisonhousebnb.com/

About 2 T stops from Harvard I think, but it has rec'd great reviws on this board.