Defect tracking tool from Rational software. Apparently Microsoft Windows only, this bug database can connect to either Microsoft Access, Oracle, SQLAnywhere or Microsoft SQL. Very expensive, this tool integrates well with Rational ClearCase, a source control and configuration management tool. ClearQuest is easy to set up and use, but is tied to Windows.
You define your database structure in a "Schema" (not an XML one), then create a database derived from that schema. Access to the bug tracking database is either through a Windows based client or a Web client.
<Whisper> I'd much prefer to use bugzilla but this was forced upon me.