To add to that list, there's also pfsense: http://www.pfsense.org/ a FreeBSD based distribution for building routers which uses the pf firewall, originally from OpenBSD. I know a number of small companies, my own included, which use it and there's even a book written about it!
I'd hazard a guess that there are similar projects based on BSD floating around for various other uses too.
I'd hazard a guess that there are similar projects based on BSD floating around for various other uses too.