Just wanted to ask everyone what is their favorite development tool. I am wanting to develop a web-based application using MySQL with web services. I have tried Microsoft Visual Web Developer 2008 Express.
That totally depends on what you need the tool to do. You should be more explicit.
For developing databases you could be wanting to generate a database scheme, generate the scripts to create the database, it's tables, views, procedures etc. Perhaps you only need a tool to modify the data in the database through a GUI.
Regarding the application, what programming language do you want to use? Perl, PHP, ASP, something else?
For developing PHP applications I use PHPEdit. A very complete IDE. For editing, modifying or other actions on a MySQL database there are several tools, like for instance Navicat, but you might be satisfied with the MySQL Workbench (either the Commercial or the Community edition) or perhaps a webinterface, like PhpMyAdmin, that can be run on the server as well.
For simple modifications or small scripts I do not even use a development tool, instead I use a simple text editor or a command line client.