I've just read Scott's new MSDN article, which I'd been putting off for a couple of days as I thought I knew a little about the subject, having written at least one useful handler myself.

What I did not realise, though, is that you can map to handler factories rather than directly to handlers, which opens up a whole raft of possibilities. Check out the article for yourself as I'm sure Scott explains it much better than I ever could.

[Aside: this is the second post in a row that follows the "I thought I knew about <blah> but <so-and-so> knows so much more" pattern. This is not a good trend ;) ]