You have a few options I can think of
1. Ad google adsense and make a little bit of money from the visitors clicking on the adsense ads (I dont like this one because it makes your website look cluttered and junkie)
2. If most of the people are home sellers that visit your site.... create an eBook (home renovations/home staging) and sell it to people that visit your site. You could create this eBook yourself or hire someone to do it. I get all my eBooks done at
Get A Freelancer (that's my affiliate link) and you can get some good work done there. If they are Buyers that visit your site.... What about an eBook on buying a property (ie. Top 5 mistakes Buyers make when purchasing a home). You can sell the eBooks for a small amount (couple dollars?). If you have enough people buying you could make a good amount of money
3. Google "real estate affiliate programs" and see what companies out there offer.
4. If your a real estate brokerage... generate buyer and seller leads and give them to your agents for a referral fee?
Jeff