This is a nice discovery.
My first use for it is:
Make a bookmark of “http://www.google.com/search?q=%s”
Go into the bookmark properties and give it a keyword of “?”
Now you can go a google search for happiness by typing the following into the address bar: ? happiness
You can do this for IMDB, Dictionary.com… anything. Slick.
Here’s what I’ve keyworded so far: