One thing I've noticed -- and this is a *very* minor nit to be picking -- when I get an email notification of a new post to a topic I'm watching, the provided link takes me to the first page of the topic. If there was some way to (preferably) take me to the page that contains the post I'm being notified of, or (alternately) take me to the last page of the topic, I think it might be a bit friendlier. It's just a thought; obviously it's not a huge deal to click the "last page" button when I get to the topic.
Avoid infestation. Rotate.