If u input your username in the search box in forums, results will lists all forum posts where anyone used your username in the body of the post ... so' it's not comprehensive.
Ji-N:
Not at the moment, but we would love to work on it when we get a chance.
A few weeks ago, when I searched Forums, I received a list of Threads I have started .... I can't remember how I did it, or if feature still exists. Now, however, I get what I mentioned above.
Still, neither provides a complete list of threads where I have posted (either started or replied).