A nice little case study and review of two remote testing tools currently on the market: Usabilla and Loop 11. Even if you're not thinking of using these tools, it's worth a look just for the narrative of how the writer approached the study.
Usabilla and Loop11: Taking remote research tools on a test drive - article by Juliette Melton for UX Magazine
I've taken a look at Loop 11 in the past too, but am still to find the right project to use my free trial on.
Loop 11 online usability testing tool