Using the MODS for Links 2.0, you can make the script do almost anything you want!
For example, if you use the following Modifications:
1) TellaFriend - To refer classified ads
2) Add new fields (not really a mod) - To add additional fields for classifieds
3) Expirator Mod - To expire ads based on date provided by classified owners.
4) Shopping Cart Mod - To add order processing.
etc., etc., etc....
Links is a really flexible program that you can adapt it for most if not all of your web site needs.
Regards,
Eliot Lee