I just love it finding new user experience testing tools. And I especially like ones that are simple, fast, affordable, versatile, and provide actionable data.
Verify is just such a tool. And unlike tools that are limited to live websites, Verify can be used to test and compare mockups.
Here are the types of tests you can run:
In this test, users are asked where they'd click on an upcoming screenshot, then shown the page. The system records where and how quickly they clicked. (Results are returned as a heatmap.) A great test for determining whether your call to action is prominent enough.