Client – "Yes, and additionally I'd like to get some usability studies done prior to launch."
You – "Fuck." (I'd advise simply thinking this part)
Let's face it, if you've been designing websites, applications or prototyping interfaces for any length of time you always get the dreaded request for a third-party usability study. Normally this means a pass-through cost that you'll never see, and endless rounds of revisions. Well a new service "Usabilla" now allows for you to serve up your work for a test audience with relatively minimal expense. Yes, you're still stuck doing a 1k rounds of revisions based on the feedback. But you'll be able to stomach the revisions knowing at least you're being paid adequately for your efforts in taking the time to test it.
The premise is very basic. You create an account, and link your test pages (or screen shots respectively) to your account and then you assign questions against the work posted. The application itself has a number of 'pre-fab' questions you can add as well.
SIDE-NOTE: The fact that you can test static comps' and wire frames is [very] nice for designers and developers too as you don't have to the work through development (wasting hours, and often losing capital) to get some definitive third-party feedback. Start to think about creating large IA's and you'll start to see the nightmare that will be your life if you push it all up on a dev' server only to have the client something like "where's registration page?" Boo.
While I've not used the service I feel it would be a phenomenal asset given the results that you received. That will remain to be seen. I might participate with this application on both ends of the spectrum to see how it truly works – if so I'll report back.