I use Sauce Labs for regression testing. Saucalabs has helped our organization speed up our release process significantly. Prior to Saucalabs, it used to take us 3 days for site regression. Site regression is now achieved in less than 60 minutes.
I love the fact that Sauce Labs is easy to setup, and covers an extensive array of browser, and device types. No more VM, and grid setup. I simply love how I can just focus on testing, and not worry about setups, and other messy stuff.