BSD Router Project (BSDRP) is an embedded open source router distribution based on FreeBSD with Quagga and XORP that fit on a 512Mb Compact Flash/USB.
BSD Router Project images files are available on sourceforge: http://sourceforge.net/projects/bsdrp/files/
More information on the Downloads page
2010-02-17: BSDRP 0.32 released
This releases brings lot's of new features:
Read the Release notes for more details.