I started using LaTeX on the Mac five years ago (with something named OzTeX or similar) on Mac OS 8, and after a long break got back to using LaTeX. After searching for information on current distributions and front-ends, I found two recommendations: TeXShop and iTeXMac. I installed both, with some problems with the i-Installer first (by default had a bad URL or something), but after fixing that, everything ran smoothly.
iTeXMac was said to have more features, but those could be overwhelming as well. For the beginner, I would recommend TeXShop, and the chances are good you'll stay with it.
Only small downside: it's version field isn't compatible with MacUpdate Desktop (which shows only 'TeXShop' as the installed version).