As a Mac user, text editors are a pain in the ass. When you're booted into OSX, you wish you had access to your Windows-only text editors. When you're booted into Windows, you wish you had access to your OSX-only text editors. Running Parallels just to edit text is over kill. ST solves this problem beautifully--on Linux as well!
The best part is that the license if PER USER instead of per machine, so you can install Sublime Text on all your different operating systems.
I also want to mention that the config files and plugins are written in Python. Yes, the config files are actually Python files. I haven't made a plugin yet, but the API looks great and simple to use.