One of the first things I did when I started learning MySQL is to find a decent GUI tool to administer the server, since I didn't think that the bundled MySQL Query Browser/MySQL Administrator is what most people use for complex work. Luckily, I was right. There is a huge variety of MySQL development tools - some better and some worse. I'd prefer if I only had one tool that does it all - but if that's impossible, the important thing now is to pick the right one for the job.
Here it is, the (nearly) complete list of 3rd party tools. It took me a while to find out about all of them - so I hope this saves people quite some time there.