For some reason, I've yet to find a web forum with an interface as useful as any random Usenet client (say, trn in its ncurses goodness). And really, that's just three features (I'll give a pass on things like killfiles) -- pick a subject you want to read, navigate threads, and don't show messages I already read (unless I ask for them). Most forums do feature 1. Some do feature 2, though often awkwardly. Why the hell is feature 3 so hard that nobody does it?

I hope Google Wave comes out well. It has all three features and may even be able to impose them on sites which don't offer #3.