Here is a list of development tools that I use and love.
Wamp stands for Windows Apache MySQL and PHP it is a simple to install local testing environment that take away all of the fiderly setup of you own Apache PHP server on windows. Their is a version for mac which is mamp.
Sublime Text 2
This is a much loved and lightweight text editor with a really nice ui and colour coding scheme
SASS is in my opinion one of the best CSS preprocessors
Compass is a development environment for SASS that come with a load of pre build mixins