Ive been using www.crossbrowsertesting.com for this. Are there any USP's here that make this better out of interest?

They both do similar things, I think that crossbrowsertesting fails when it comes to testing localhost though. I don't think you can just run a rails app by pointing to where the files are, since rails runs on its own test server activated through the terminal. If you are only testing basic html/css then it will work fine

Same here, this is my default for cross browser testing. Setting up virtual machines was somewhat of a headache, and the speed at which I can test different browsers is awesome. They also allow localhost to tunnel into the site so you can test your builds extremely quickly. Highly recommend!

Having to fix an IE7 bug, this saved me the other day - super awesome and great tool for developers!