Specifically for the classifieds section:
1. Ads that automatically expire (i.e., deleted) after a year (or some time limit), unless prompted by the user to extend. Parang sa Sulit.
2. Searching by tags, in addition to keywords. I would tag a Boss DS2, for example, with "Boss" "DS2" "pedal" and "distortion". Tagging could be limited (e.g. 5 tags) or moderated to minimize unrelated tags.
3. In the user profiles, a feature that will segregate the "topics" (started threads) stats of the user. For example, when viewing my profile, you can see that I have 5 threads created in the "Classifieds: Guitars". Now it's just one continuous list. This way, we can sort of have user "stores".
4. Segregating your bookmarked or followed threads, within your own user control panel. E.g., threads that you have followed within "Classifieds: Guitars" will be grouped together.