As this site grows, finding old posts will become infeasable. I think that we need some way to track your activity so that you can "re-find" them. A quick and easy solution would be something like a "User Activity" tab from your user profile. When the tab is clicked it would reveal a list of all questions asked, answers, and comments.
I didn't see this in my initial search, but it looks like [this has already been requested](/meta?q=233)
To expand further, I might add that since there aren't many public sites yet on TA, initially a single "Activity Log" would be sufficient, but at some point site-specific Activity Logs would be ideal.