PICK Database (Score 2, Interesting)

The PICK database (aka D3) is a little known database that's been around for about 20 years, and was ported to Linux about 4 or 5 years ago. This DB is fully implemented on Linux, and I've talked w/ people that have 1000+ users running. The DB itself has several million user-licenses in the field, and a lot of them are running Linux. The Linux implementation supports multi gigabyte DBs and the user count is limited mostly by the power of the machine. I think this counts.