I'd really like to see O'Reilly put out a "Vim Hacks" book, but in the meantime, there's a Hacking Vim book which has just come out. I should see if I can find a decent technical bookstore in London and check it out (oh, for a Powell's Tech in London!).
In the meantime, I should probably scrape together all of my vim hacks and post them somewhere. I'd probably learn from them since I've use them a lot and just forget 'em, but it might be nice for others to have, too. Critiques would also be useful since I pretty sure I'm declaring variables incorrectly in some plugins.
(I seem to recall that Damian's writing a vim book. Can't wait for that!)