SGNX  on the mactex site, there's a linked page

http://www.tug.org/mactex/morepackages.html

where there's this thing: BasicTeX-2008 (54.1 MB). i never tried it before but from the description it should be relatively capable for its size.  
(Version 2.0.0)

SGNX  latex is a whole self-contained system for producing scientific documents that can contain complex equations/tables/graphics/much more. it is quite the standard in academia. latexit, on the other hand, is more like just a little "widget" that lets you test some thing or cook up some snippet real quick.

i personally think mactex is the best latex package (in terms of ease of installation/usage and speed, and the integration of different parts) among all platforms; and latexit is just a sexy little kit that comes in quite handy now and then  
(Version 2.0.0)

SGNX  still, connection drops upon keystroke when connecting to windows 7...  
(Version 2.0.1)