I love how Blackboard, despite years of legal intimidation and generally anti-competitive practices, is slowly being picked away at by the competition, not from some monolithic replacement but by smaller, targeted services that do one thing really well. Tabule looks very interesting. Two of my classes this semester are using Piazza for online discussions. What Piazza does to stop spammy emails is let you set a digest to aggregate all messages every n hours, which I really like.