From the Devs:
You’re writing an email to invite a friend to meet at a local San Francisco restaurant that neither of you has been to. You’d like to include a map. Today, this involves the disjointed tasks of message composition on a web-mail service, mapping the address on a map site, searching for reviews on the restaurant on a search engine, and finally copying all links into the message being composed. This familiar sequence is an awful lot of clicking, typing, searching, copying, and pasting in order to do a very simple task. And you haven’t even really sent a map or useful reviews—only links to them.
Okay, that's somewhat long winded. Short version, being able to use Google Maps and Google Mail to quickly send someone directions is cool. Also being able to do in place highlighting and then email without having to do a screen cap and edit session is a time saver. Calculator? Sure. And plenty of other tricks for a pure alpha.
I'm hooked. No shock.