In this screencast we have CodeKit start watching our project. This makes lots of developer tasks much easier.
The first thing we do is us it to losslessly optimize an image. Easy one click.
Then we install Compass in the project. This gives us the ability to use CSS3 mixins provided by Compass, instead of having to create our own, which we should surely do a worse job.
Perhaps most importantly, Compass (through CodeKit) now watches our project folder and automatically compiles our .scss files into .css that we actually use. As an added bonus, when save our .scss files in our code editor, those new styles are "injected" into the page automatically, which is awesome.