It seems that so many systems subscribe to the same system of searching for users: direct solicitation. Though large systems for large companies will continue to be sold as complex sales, the smaller services can be sold via referrals or reference. Roomster.com is again an example for consideration. They make their listings easy to find by search engine and manually-shared link. They even have their Roomster Facebook application! Way to use the social networking site to network. They have 450 fans and almost 7,500 monthly active users. Not the most popular application, but surely a solid one in the real estate rental arena.