Google Maps Envelope.

Google Maps Envelope is an interface for Gmail and basically gives you the option to send the letter physically instead of electronically. Dope!

“Rahul Mahtani and Yofred Moik have conceptualized the addition of a “Send Envelope” button that would enable users to quickly send a physical letter — rather than an e-mail — with spiffy Google Maps-esque packaging.

Upon clicking the “Send Envelope” button, Google would print and deliver an e-mail via the USPS for a small fee. The return address label is in a bubble at their start of a route traced on the map envelope, while the destination is in the address bubble at the end of the route. Between the two is the route that the letter takes to get there.”