1) When hiding/watching a topic, return to the topic list rather than the topic itself (why on earth would you want to carry on reading a topic you are hiding ?). Or, alternatively, the ability to select a whole load of topics and hide/watch them in one go ?
2) Nested posts ?
3) Ability to remove threads from the "I'm on" section
Good suggestions. I would also want to do something with the number of local topics - nothing wrong with having them all but when selecting topics to hide you have to scroll through all of these things and there's pages of them.