...well sort of! This site allows you to view screenshots of your site in many different browsers. This is very useful to see how various browsers are rendering your css/code. http://www.browsershots.org/ (no relation!) Nice! Notting
This is a neat tool, but to be honest, most of the time it is not very practical. Here is why: 1)You have to wait up to 30 minutes (sometimes more) to view what the web page looks like. If I had to wait for 30 minutes every time I wanted to view what every change I made looks like, it would take me years to put together a web site. 2)It takes less than 30 minutes to install FireFox, IE6, IE7, Mozilla, Opera, and any other browser you need to test. 3)If you forget about it, your session expires, and you lose another 30 minutes trying to see what it looks like. The only thing that is truly helpful about it is the ability to view your page at resolutions larger than you can currently view on you computer. However, if the page is coded correctly, layout usually doesn't break when viewed at higher resolutions. Like I said, it is a neat tool, but quite impractical.
I use this all the time!! of course I have most of the major browsers already installed, but it is often nice to see how your site looks in some of the more obscure browsers, or in older versions of browsers that you have currently installed