A co-worker told me about this one… SQuirrel SQL bills itself as a “universal SQL client”. At work we use Oracle and I’ve been happy using Oracle’s SQL Developer. At home on Linux I’ve been searching for something to interact with MySQL. The MySQL Administrator and MySQL Query Browser tools provided by MySQL work but are lacking in features…
After using SQuirrel SQL for a few days I’m happy to report my search may be over! SQuirrel SQL is like Eclipse – it’s based on Java, uses JDBC drivers to connect to your database, and it can be extended via plugins.
All the basics are here – code completion, SQL editor, auto correction, editing results, etc. Through plugins you can get table relation graphs, data import, database copy, SQL validation, syntax highlighting and more.
Since SQuirrel SQL is based on Java it’s cross platform, it supports any database with a JDBC driver and is free!

Another excellent tool is SQLYog, over on http://www.webyog.com/ – I’ve been using it for a while now and never wanna go back to another tool.
Looking at SQLYog – it requires Wine to run on Linux.
That’s correct, but as I use both OS’s (Windows and Linux Ubuntu) it’s nice to have one piece of software that runs on both ;-)
I’m gonna download Squirrel SQL and play with it for a while, see what it does for me!
Navicat has a lite version for free which is very nice for mySQL
http://www.navicat.com/
@Sebastiaan if you try it I’d love to hear how you think it compares to SQLYog.
@Brian – I did look at Navicat but it was missing some basic features in the free version – code completion, import/export, etc.
i find that for a piece of software that i really enjoy using and is beyond helpful i don’t mind paying for it. i use aqua data studio. it’s built in java (cross platform), and connects natively to the big boy db’s. it also will connect to anything using odbc or jdbc. there are things i would like it to do, but it does EVERYTHING i need it to do and more. i highly recommend it.