Quickly testing Android apps on your laptop without having to deal with an emulator?
Concrete example, I've just finished the first beta of our companies new Android app. Now I want to show everybody in the company to get feedback and generally let them know what is happening.
Hard: Convince everybody to install the beta on their phones, and then convince everybody with an iPhone to borrow an android phone and test it there.
Easy: Send everybody a link that they can click and have the latest beta show up running on their desktop.