Grunt.js lets you automate those tasks, that you'll likely do every other minute with very little effort. By little effort, I mean typing some commands in the Terminal. Through some Node.js magic, boom automated workflow
Oh Boy, That Sounds Complicated
Yeah, well hasn't everything with web design seemed complicated? At first it probably did. But most of us took it bit by bit, cleared a path through it and lived to tell the tale. There is somewhat of a learning curve. But guess what? It's not so complicated. Chris Coyier gave us a great introduction with his 24 Ways post & a nice video tutorial on CSS-Tricks.
Basically, you setup two files in your root folder, package.json and a Gruntfile.js/Gruntfile.coffee. Hop out to the command line and install Node.js and the CGI for Grunt, globally. Then you change your directory to back to your root and choose some tasks to run. For instance, compiling your SASS files into CSS. Install the Node module that automates that task, configure it and you're done.
But what about Codekit?
Personally, I think Codekit will get better over time and give more options, more flexibility. But in really, Codekit shouldn't bend and break for every whim, need or idea of how you work. That molds and changes from day to day and project to project. And so should your solutions.