MAMP: Macintosh, Apache, Mysql and PHP. A simply installed installation of the holy trinity of rapid, open-source based, web development. The thing that's always kind of been a drag, even if you're used to it, is installing and configuring apache and mysql (I haven't actually done any PHP myself, but having looked at installing it, was immediately bored by all the config params etc).
They even have a nice dashboard widgit for stopping and starting services. Pretty awesome.