A client needed some help with a display issue on Safari / Mac. Browsercam is a good solution and is reasonably priced, but for this simple issue I just needed to see the site in Safari / Mac and make sure I hadn't affected IE6 as well.
Browsershots is free and has a huge variety of browsers on the three major platforms. The turnaround can be pretty slow (2 1/2 hours in my case) so sure you set the "Maximum wait" to 4 hours.
With a free, easy to use service like this, there's no excuse not to expand your browser testing a bit.