Since developing for iPhone OS 3.0 I've been creating, editing and maintaining sqlite databases. The command-line tool "sqlite3" is quite nice to use but sometimes you just want a graphical editor.
Mike Titlebaum has created the ridiculously literally named: "Mike T's SQLite Database Administrator Tool". It's free and even goes further than the basics to offer an import function, SQL query autocomplete, a comprehensive schema view and export functionality. You can also create new tables and edit data.
It does have its quirks but for a free app it's worth a look.