I tried bookmarking some forum threads and spent a long time trying to find those bookmarks again. I finally found out that I could find them by clicking on controls in the forums tab. I think the most logical place to have your bookmarked threads would be the page you get to when clicking in "My Geek".
I think both subscriptions and bookmarks would be better to have on that page. It might also be a good idea to be able to reach the other preferences found at Forums/Controls from your user page.