For those either just getting into unit testing your applications (maybe even TDD) or those that are old hat at it and what to figure out a few more tricks of the trade, you should check out this latest post from Chris Hartjes about some of the tools he uses to get the job done.
So how does the Grumpy Programmer write code, TDD style? It starts with using a set of tools that reduce the amount of friction required. First, I do almost all my work from a terminal. [...] Why the terminal? PHPUnit is a CLI application. Yes, many popular editors and IDE's can do things like execute PHPUnit for you, but they are limited in what flexibility they provide.
He also talks about his editor of choice, vim, and some of the plugins he uses in his day to day testing development. This includes tools to handle things like interfacing with git/gists, working with ctags to see the code's structure, working with "surroundings" and the pathogen plugin to make adding other plugins easier. He keeps the code up in one terminal and his testing tool (PHPUnit or other) accessible in a second, making it a simple matter of switching to write the test then the functionality to make it pass.
If there is a lesson to be learned from this, it's to make sure that every tool that you use reduces the friction that is generated when building your application using TDD.