open ~/Desktop/MyWordDoc.doc [will open in MS Word]
open -e ~/Desktop/MyWordDoc.doc [will open in TextEdit]
open ~/Desktop/*.doc [opens every Word document on the desktop, in Word]
open http://tuaw.com [well, give it a go!]
I use open in installation scripts or other situations where I want a GUI application to come up at the end of a process. For example,
open /System/Library/CoreServices/Software\ Update.app/
launches Software Update and begins checking for available patches. Sure, you can force an update with 'softwareupdate -i -a' anytime, but maybe I want to give the person sitting at the console an opportunity to select the updates needed, or cancel out of the possibly-lengthy update cycle until it's more convenient. You could also use the URL functionality to take people to a 'readme' website... the possibilities are manifold.