Just found this:
dblint.codeplex.com/It's written in .Net and analyzes your database schema (and apparently data) for potential problems.
Just ran it on an MS SQL db, also runs on Firebird, PostgreSQL and more.
Only ran it on the one db which I thought was well designed; still it flagged some entirely valid issues.
Perhaps a nice thing to use when designing databases...
Oh, and it's open source, so if somebody wants to port it to the Lazarus Database Desktop