A GNOME frontend / client for accessing SQL RDBMSes. It supports - via plugins - many RDBMSes, like PostgreSQL and MySQL. Written by Matias Mutchinick and José Miguel Ronquillo.
It's very clear program and you don't need to know SQL (much) to create/browse tables and enter data.
It also comes with Debian...
Home: http://gtranscript.sourceforge.net/