I agree ... about the ignore threads feature. A list of ignored threads for each member would be handy. If it can be added and not create issues with loading down the system or breaking the system etc, then that would be excellent.
For example ... a proper ignore of a thread would hide the thread, such as a thread that is under a particular forum section where the section is assumed to not have threads used for a personal blog/diary ... and which should possibly be in another section ... such as meta or a blogs section etc. And that is all ok. This is where a proper ignore thread feature will work. There will be a need for each user to have that control feature though ... convenient access to their own ignore list, where they can remove ignored threads etc.
I do agree with a couple of people on this. About the ignore feature. It can certainly be worked on later.