Here's an idea: if a topic only has a new post from a user on my Ignore list (I'm talking about you ChartBuddy), it shouldn't show up on my Watchlist.
I like the sound of it. The problem is, it involves two things (user ignore, and the watchlist) that aren't present in my branch of SMF. There's no harm in posting ideas that I can't currently work on, though: I expect that I'll be able to work on them at some point.
This reminds me of the "bug" that I incorrectly reported here[1]. It didn't reach any consensus but I really believe that if I created a thread in a board that I have on my ignore list - due to numerous reasons - because it was the right place to do it, I should still be able to see it on my profile (for updates and such). I know that there's a workaround by just allowing the board to show up during a specific period of time, but I don't believe that is a balanced solution considering that someone in the future may post in the thread and I wouldn't be able to know it if I had the board ignored.