Jeffrey Zeldman posted yesterday about a new service that will test designs over multiple platforms.
BrowserCam is designed to simulate what a site will look like on multiple system combinations without you being required to setup a new computer and do the testing yourself. So far, I have tested the system using the demo for myRPHA.com as well as this site (see results) and it has been working ok giving quality results. I downloaded the screenshots and each test was a 1024x768 jpg averaging 450kb.
There were still a number of issues with speed and specific browsers crashing that will prevent me from buying the complete test at the moment but as the system grows I could easily see myself spending the $10 US for 10 URLs for a complete test on multiple resolutions.