On OS X 10.8.4, I set the Finder to open all .txt files with SublimeText.app
Now when I doubleclick on a .txt file in the Finder, it launches ST (obviously)
What's funny is: ST launches and displays the file before the Finder shows it's animation of the file icon launching.
It makes for a pretty funny effect. I would make a screencast of it but dont want to take the time.