How would you turn a free classifieds website into a business?

All, I inherited an antiquated classifieds website from a friend last year and have been in the process of rewriting the UI in a more flexible and cheaper to host technology. I have a designer lined up to help created and updated look in March because I’ll admit that the design is very 1.0 and the usability is less than awesome. I am on the front page of google for the term “yard sale” and am in the #1 or #2 spot for the terms “online yard sale and “online garage sale” I get a couple hundred users per day and have a 38% bounce rate. The user base tends to produce pretty high click rates so it more than covers the hosting fees. I want to take this website to the next level of being a business and I have some ideas but I wanted to solicit ideas and advice from the Hacker community at large. I am not looking for advice regarding technical changes or look and feel because that is all in the works. You can see the original 1.0 version here www.frimp.net