MySQL
MySQL began as a niche database system for developers but grew into a major contender in the enterprise database market. Sold to Sun Microsystems in 2008, MySQL is currently part of the Oracle empire (January 2010). More than just a niche database now, MySQL powers commercial websites by the hundreds of thousands and a huge number of internal enterprise applications. Although MySQL's community and commercial adopters had reservations about Oracle's ownership of this popular open source product, Oracle has publicly declared its commitment to ongoing development and support.
