Please take a look at the ports page for info on software packages ported to FreeBSD. The list currently tops 7,000 and is growing daily, so come back to check often or subscribe to the freebsd-announce mailing list for periodic updates on new entries.
Most ports should be available for the 2.2, 3.x and 4.x branches, and many of them should work on 2.1.x systems as well. Each time a FreeBSD release is made, a snapshot of the ports tree at the time of release in also included in the ports/ directory.
We also support the concept of a ``package'', essentially no more than a gzipped binary distribution with a little extra intelligence embedded in it for doing whatever custom installation work is required. A package can be installed and uninstalled again easily without having to know the gory details of which files it includes.
Use the package installation menu in /stand/sysinstall (under the post-configuration menu item) or invoke the pkg_add(1) command on the specific package files you are interested in installing. Package files can usually be identified by their .tgz suffix and CDROM distribution people will have a packages/All directory on their CD which contains such files. They can also be downloaded over the net for various versions of FreeBSD at the following locations:
or your nearest local mirror site.
Note that all ports may not be available as packages since new ones are constantly being added. It is always a good idea to check back periodically to see which packages are available at the ftp.FreeBSD.org master site.