Yes, a conversion of 1 out of 7 is quite good. 48 visitors in 35 days is quite bad.

You need to start promoting that site. It should be in your sig. You should be posting on student-related forums. If the income you get from rentals is large, I would take a portion of that and apply it to Google Adwords. Get the ads out there, and hope you make it back on the first rental. If you don't, buckle down and keep plugging away.

Also, if there is nothing to the site but rental signup forms, then no wonder nobody bothers. You've got to create a community around it. And I don't mean "install a forum." I mean, write articles. Get advice columns running weekly or monthly. Get tutorials like, "how to eat for a month on $50." You know, stuff that students would be interested in. And make sure it's Google-friendly (no query strings in your URLs -- just plain HTML files that have good text content).

Good luck.

-T