Any good general directory would have a real estate section - for a niche site check out http://www.36towns.com/
I launched my real estate directory a few weeks ago and you can get 35% off a review for inclusion by using coupon code pre35
Already a huge thread regarding this. http://forums.digitalpoint.com/showthread.php?t=636539&highlight=real+estate
Try http://www.ired.com/ used to have really good PR, but seems to of taken a beating in the recent changes in google to penalise sites which sell ads.
These links should help (several repeated from above): http://www.web-directories.ws/Niche/Real_Estate/ http://www.directorycritic.com/realestate-directory-list.html http://www.directoryrate.com/real-estate-directory-list.php http://forums.digitalpoint.com/showthread.php?t=636539&highlight=real+estate http://www.google.com/search?hl=en&q=real+estate+directory
You're back! Where have you been hiding? Check www.biz-giant.com - Malcolm is building some useful niche directory lists.