The TeX collection DVD includes MacTeX, which is a Mac-tailored version of TeX Live; details may be found on the TUG web site. If you don't have the disc, you can download the distribution from CTAN (but note that it's pretty big). MacTeX is an instance of TeX Live, and has a Mac-tailored graphical TeX Live manager, so that you can keep your distribution up-to-date.
Note that installing MacTeX requires
root privilege. This
is a pity, since it offers several extras that aren't available via a
standard TeX Live, which aren't therefore available to “ordinary
folk” at work. For those who don't have
root privilege, the
option is to install using the TeX Live
OzTeX, by Andrew Trevorrow, is a shareware version of TeX for the Macintosh. A DVI previewer and PostScript driver are also included. OzTeX is a Carbon app, so will run under Mac OS/X (see http://www.trevorrow.com/oztex/ozosx.html for details), but it is not a current version: it doesn't even offer pdfTeX. A mailing list is provided by TUG: sign up via https://tug.org/mailman/listinfo/oztex
Another partly shareware program is
CMacTeX, put together by
Tom Kiffe. CMacTeX is much closer than OzTeX to the Unix TeX
model of things (it uses
dvips, for instance). CMacTeX
runs natively under Mac OS/X; it includes a port of a version of
Further information may be available in the MacTeX Help page.