Some notes:
"Here are the 5 most recently updated of your applications."
How about, "Your 5 most recently updated applications:"
I couldn't see anything to do with the applications, they're all just listed as "Not started".
"We're taking the headache out of the apartment rental applications."
The "out of the" should be "out of".
Should have calendar field for dates.
Pages keep timing out, news.y effect? Attachment uploading failed to be maintained across an error with another part of the form.
No indication of whether emails are going to applicants, no way to change from accepted to rejected or vice versa once you press that link. Not sure if you sent anything to the mailinator address I signed up with, but couldn't see anything there.
It really could do with pictures. Lease terms (e.g. renewal length, price).
If you're taking people's SSN numbers, I guess you would want to do that over SSL. Give an alternative for people too nervous to do that.
Maybe put a flow diagram of how it works on the front page. A privacy policy would probably be a good idea too.
No way to cancel an application after it's been accepted? No way to communicate with the broker through the site?
It looks like it has potential, but I think could do with a bit more design and iteration. What's going to attract people to the site?
---
Edit: more...
Do you really want to make those URLs case sensitive? When I get the case wrong I get a list of all brokers, but if I try to select any apart from Joe I get an error saying I can only select Joe. Why the error? Why show the others if I can't select them? The combos don't seem to be linked up.
As an unlogged in user why can't I view the properties that are available?
--
Good luck
Edit: more on why email through the site:
I think you either want to explicitly encourage people to use email to ask questions, or have a communication mechanism built in. The main advantage of having a communication mechanism built in would be that you can keep track of all the communication about a particular property in one place. It also makes your site more sticky, as there's something to do other than clicking "accept" or "reject". Even just adding notes to the "reject" would be helpful. I think it naturally leads into keeping communication around the seed of the conversation, which is the lease.
--
After all, you're trying to add value here, if you're just directing people to sort it out over email then make it clear what the benefits of using your site are beyond it just being a directory of brokers and properties.