If you do not have the resources to get a testing room furnished with at least 10 computers http://www.spoon.net/Browsers is the best alternative!
For people who just want to see screenshots of their site in different browsers for a cross-browser test, there are several multi-browser screenshot services available. Smashingmagazine.com tested most multi-browser screenshot services and wrote a in depth report about it. The table below is the outcome of their test.
||Price (1 year)
||IE, Firefox, Chrome, Opera, Safari, Dilo, SeaMonkey, Minefield, Epiphany, Flock, Galeon, Konqueror, K-Meleon, Avant, Netscape, Shireteko, Kazehakase, Iceweasel
||IE, Firefox, Chrome, Opera, Safari, Konqueror, Camino, Netscape, AOL
||IE, Firefox, Chrome and Safari
||Free (till end of 2010)
||IE, Firefox and Safari
||IE, Firefox, Chrome, Opera and Safari
||IE, Firefox, Chrome, Opera, Safari, Flock, Camino, SeaMonkey, Netscape
|Multi Browser Viewer
||IE, Firefox, Chrome, Opera, Safari, Flock, SeaMonkey, Netscape, K-Meleon, Camino, Konqueror, Epiphany, Kazehakase
||IE, Firefox, Safari