In this section, you will find several tools which may be useful to developers.  There are many tools out there to assist developers in building applications, so it’s important to use the right ones.  Here is a list of several helpful tools which will help you in developing your application:
JustHost – You will need to find somewhere to host your application. JustHost.com is an excellent choice and you can now take 20% off your hosting costs when you use coupon code JHSL20.

PHPDesigner - A free PHP editor which you can use to put your app together

PHP Client Libraries - These are required to interact with Facebook Platform, in this page you can find several official, unofficial and third-party client libraries for various platforms.

Facebook’s API Test Console – Use this tool to experiment with functions and responses, and see what content Facebook Platform makes available.

The Facebook Developer Forums – This is probably THE most helpful tool you can find.  The Facebook Developer Forums are filled with helpful suggestions and thousands of other programmers.  You can post any question you have and you will usually get a reply, either directly from Facebook or other programmers.

Facebook’s FBML Test Console – With this you can experiment with FBML.

Facebook’s Feed Console - Use this tool to register a new template bundle on behalf of any one of the applications you own.

Application Demos – This section holds a variety of Facebook Application demos in various languages and platforms.

I will be updating this section constantly.  If you think I missed something feel free to post it in the comments.