The 
Oracle Corporation, headed by one infamous CEO Larry Ellison, claim that 'Oracle Corporation provides the software that powers the InterNet', although that designation probably goes to IOS written by Cisco. Their most notable software product is their RDBMS, aptly named Oracle DataBase.
See also:
Oracle8 Database HOWTOOracle7 Database HOWTOThe Oracle FAQ
DavidHallett, who hasn't wikied his considerable experience getting this DataBase working on Linux, particularly RedHat.oracle-wiki (german) (german.)Oracle 10g DocumentationOracle 9i DocumentationOracle 8i DocumentationOracle 7 Documentation