I don't know if I'm the only one, but there are really only 3-4 sub-forums that I visit 99% of the time. I find myself keeping a topic tracked in each so I can have quicker access to them when I want to visit them, instead of scrolling to them. This is especially useful when I'm on my phone. What I'm suggesting is to be able to 'mark' sub-forums that one would want to track, so we can have quicker access to them, and have some sort of link up there by topic tracker, or even part of topic tracker, maybe label it forum tracker.
Most of us frequent sub-forums that are not listed directly on the main forum page, but rather as a sub-link next to several others, and it just cuts down on the time scrolling for it. Unless you're like me and just track topics in those forums for the purpose of tracking the sub-forum. I don't find this to be a huge problem or anything, but I know I would use the hell out of this.