Realty Manager from InteractiveTools.com is the best script I have every worked with - all of their products are excellent. From easy installation (or they will install the scripts free for you!) to professional interfaces to prompt, personal service to user editable templates, you couldn't ask for more in a software or a software company. Everything about working with InteractiveTools.com is a pleasant experience.
As a developer/designer, not only do I appreciate the reasonable cost and fast time to market, I also appreciate the way the software reflects positively on my company. The user interfaces are clean and professional. The product is stable, fast and reliable. The administration is simple and intuitive. Even your most unsaavy computer user will be updating their files in no time. And the templates can be completely customized to work with any site design.