The Cambridge Center For Adult Education offers a wide range of classes on art, computers, languages, cooking, photography and more. (Visit http://www.ccae.org/catalog/courses/ to see the complete listings.)
I've taken three classes there so far and my experiences have been mixed. I took a beginners painting class and was yelled at by the teacher for painting while she was talking. I think she taught at grade school during the day and just couldn't make the shift to teaching adults who are in a class for recreation, not a grade. The wine tasting class was much more enjoyable (and the instructor did not take himself too seriously!)
I'll be back though for more classes -- they aren't very expensive and its such a great way to try something new.