There is one called Opera, there's also Safari for Mac users and various ones for Linux etc. It's not always feasible to test them all out on your machine, but there's a free website called Browsershots
that you can put your url in and after about 10 - 45 minutes depending on current load, you'll get screenshots of your website as seen by various mac/windows/linux browsers. It takes a little while but its free. Commercial/paid for variants of this are sitevista click here and browsercam click here - these are obviously quicker than the free site and offer a few more options. Browsercam for example offers Blackberry and other mobile browser options plus VNC remote access that allows you to test interactive elements like rollovers, flashanimations and drop down menus. It has a free 24 hour trial.
Hope this helps some.