Whether you design sites on a Mac or a PC, chances are you won’t always have immediate access to all the popular browsers. As a Mac user I sometimes need to test sites in IE 6 & IE 7.
For IE 7 I can reboot my iMac with Vista, but when I need to test in IE 6 it usualy involves booting an old PC which is not only slow, I also then have to worry about whether the antivirus is up to date etc.
Thanks to Browsershots I can test my sites in IE 6 & IE 7 and a list of other browsers from my iMac. You do sometimes have to wait a few minutes to view the results and there are limits on the amount of tests you can run per day, but it’s a free service. You can even test a site in IE 4!