Thankfully, there are better, free alternatives out there to either Angel or Blackboard. Sakai (http://sakaiproject.org/) has the more substantial "big school" base, and looks like a good platform on which to build if you're okay with a Java app stack, and willing to put up with some "design by committee" architectural choices. Moodle (http://moodle.org/) on the other hand is much easier to get up and running quickly (it's just a standard PHP app), and has an active community of extension, theme, and patch contributors, albeit at the cost of some of the typical PHP framework's tendency to grow warts.