I've heard some good things about UIUC's online program [1]. My spouse took some graduate level electrical engineering classes at Columbia's online program [2] and had a mixed experience. Some of the classes were really good, but in some cases the adjunct profs weren't very dedicated to teaching; then again, failure to maintain quality control on professional instruction is a problem at lots of reputable schools.
[1] http://www.online.uillinois.edu/
[2] http://www.cvn.columbia.edu/