I am giving you few open source application to download I hope they will help :
ReOS is a web based real estate listing management application. Everything you need for a real estate web site. For Sale, Rentals, Holiday rentals, many property types, unlimited images, location, private area for sellers/buyers, newsletters, etc..
Real estate project is searching property, rent property, listing of property, rent house, villa, plot, home and flat. User can sell and buy flat, property by posting and listing their property. This project is web based with jsp and mysql database.
A complete real estate management software package : Completely web-based, set site colors, titles and layout all from the administrator login. Includes user signup, listing creation, printable listing format and many more features.
MaklerPlus is a Web based application for real estate business. It can be used to administrate real estates with an unlimited number of illustrations per object. It includes a smart content management system.