I NEVER require users to login. Let's face it, everybody hates that. But, please consider registering with my site so you can use an MLS portal. With an MLS portal you can search the real MLS in real time! You can also save your favorite properties to come back to later. You have the exact same MLS the agents use when searching for properties.
Oh, and you have my word, I will not spam you with listings just because you're using my site to search!