FreeBSD Forums user Taz has put together a very detailed howto showing you exactly how to setup a minimal FreeBSD installation with the OpenBox window manager.
If this is something you’ve been wanting to do for awhile but didn’t know where to start or what to tweak etc, have a look. You can’t go wrong.
After deciding that FreeBSD was going to be my new primary OS the question was “how to set it up for desktop usage?”. FreeBSD handbook helped me with this a lot in the beginning. But if you follow the handbook you will probably end up with GNOME or KDE desktop environment and this “how to” is about minimal but functional desktop on FreeBSD.
Fact is that FreeBSD is more than capable of being a desktop OS the only question is what are your own preferences/requests. Mine were: minimalism, functionality, speed, low memory footprint and avoiding linuxisms.