I’m currently designing a database (MySQL) for the new version/bug/task tracking system. For that task I’m using DBDesigner 4. It’s a free open source application designed to visually build databases. And it’s written in Delphi . To bad I don’t have Delphi 7 installed, otherwise I could have fixed few "design flaws" in it. I’ve used it for few days and have had no problems with it, except for a small annoyance in the table editor.
DBDesigner is now part of the official MySQL tools and it goes by the name of MySQL Workbench. I haven’t yet tested it so can’t say how it works. It still seems to be in Alpha stage (???).