This is the more preferred method of obtaining a distribution since most people will need something outlining the basics of the OS and how to get up and running with it. Also, get a book or package with the lastest distribution. You can get that information from linux.org or links from it. Some of the more common ones are RedHat, SuSE, Slackware, Caldera, and Debian. This package is only for the hardcore UNIX nut and does not support anywhere near the number of components that Linux supports.
Documentation is very hard to come by as well.