Years ago, I decided that messing with Linux configuration was an evil time sink, about on par with watching bad TV. But sometimes you're in one of those moods, and just want to waste time...
In a fit of random curiosity, I installed VirtualBox, Ubuntu and XMonad on my Mac, and decided to spend a couple of days messing around with XMonad. I figured that once I'd played with XMonad for a bit, I'd happily go back to using my Mac.
A week later, I ordered a new Ubuntu laptop from ZaReason and gave up on my Mac completely. I just couldn't bear to leave XMonad. I loved having all my windows laid out automatically. I loved knowing my Emacs and terminals are exactly 80 columns wide. I loved using every pixel of screen space for code and unit tests. Now, the idea of manually dragging windows around the desktop makes me feel frustrated.
Basically, if you're the kind of person who loves vim or Emacseven if you're a Mac useryou might want to check out Awesome or xmonad. They're not for everyone, but they might be for you.