I’ve often used browsercam for testing my sites in different browsers on different operating systems. So I can pass a URL (which must be publicly available) and see screenshot results on Windows, Linux and Mac across just about any browser you like…from Flock to Firefox and Safari to Konqueror. A full browser list can be seen here.
Now browsercam is also cool because it lets you devicecheck, meaning testing your site on Blackberries or Windows Mobile…nice :) Only problem is that browsercam is commercial, so if you’re a sole trader you may not have the budget for what is such an ESSENTIAL part of web development. You absolutely and categorically must check your sites in different browsers and operating systems!
Thankfully there is a free tool out there to help you out. Browser Shots does pretty much the same thing as Browser Cam minus the cost of course. Testing is available for Windows, Mac and various flavours of Linux with a tonne of browsers!
The only possible downside is that your screen shots are publically viewable. If that’s not an option you may need to use something else.