Just discovered this; it's nice to have things like C-w (delete last word) in all (Cocoa) apps, as well as the ability to jump between words without using option+an arrow key. There's even marks, although they aren't as useful as in vim or emacs as the text field doesn't seem to automatically scroll back up...
Here's my DefaultKeyBinding.dict (it goes in ~/Library/KeyBindings):
http://sporkage.com/DefaultKeyBinding.dict