OS X browsers

I am testing out websites for my employer using different web browsers and wanted to know if there are any OS X web browsers that are widely used?

But being new to the Mac I am not sure if I have covered enough bases for Mac users.

I have tested the sites in OS X using Firefox and Safari and have tested the sites in other OS's as well using other web browsers (IE 6, IE 7, Opera, Konqueror and e.t.c).

Well all you have to test is the engine. Firefox and camino and Netscape use the Gecko engine. Safari, and OmniWeb use the Webkit engine. And then there's Opera. And then there's IE. If I test on these four main engines, I'm confident that it should work with other browsers using the main engines. Of course, there are differences in Safari 3/2 as well as IE 6/7 so you should watch out for those.