BerkeleySoftwareDistribution, or perhaps BusinessSystemsDevelopments.

"*BSD" is often used when talking about FreeBSD, NetBSD and OpenBSD as a group. They all originally came from the same source code, the Berkeley Software Distribution from the University of Calfornia, Berkeley. 4.2BSD was perhaps the most influential version, released in September 1983. They are all released under the BSDLicense.

Has a few Old distributions:

• 4.3BSD_Net/2
  The first almost clean release. Was released with 6 missing files so it wouldn't need a AT&T UNIX licence. (wich didn't help much anyway).
• 386BSD
  Bill Jolitz free BSD wich was the fondation for NetBSD and FreeBSD.
• BSD/386
  BSDis first commercial release over wich they were sued together with University of Carlifornia by UNIX System Laboratories.
• 4.4BSD-Lite
  The blessed release, everything based on this has a get out of jail free card thanks to Novell. This release is what came out from the USL suit.

Has a few Free distributions:

• FreeBSD FreeBSD.org
  FreeBSD is an advanced operating system for Intel ia32 compatible, DEC Alpha, and PC-98 architectures. It is derived from BSD UNIX, the version of UNIX developed at the University of California, Berkeley.
• NetBSD NetBSD
  NetBSD is a free, secure, and highly portable UNIX-like operating system available for many platforms, from 64-bit AlphaServers and desktop systems to handheld and embedded devices, and even PlayStation2.
• OpenBSD OpenBSD
  The OpenBSD project produces a FREE, multi-platform 4.4BSD-based UNIX-like operating system. Our efforts emphasize portability, standardization, correctness, proactive security and integrated cryptography.

and a few others:

• BSD/OS BSDi
  The commercial BSD.
• Berkeley DataBase

etc...

As quoted by fortune(6): There are two major products that come out of Berkeley: LSD and UNIX. We don't believe this to be a coincidence. -- Jeremy S. Anderson

Good things Berkeley gave us:

• TCP/IP (aka Berkeley sockets) and related tools
• GEOS for the Commodore 64
• The BSDLicense

Bad things Berkeley gave us:

• csh(1)

Yet Another Three Letter Acronym

See also CategoryOperatingSystem