I like the Peek Definition feature in VS 2013...............
It saves opening up thousands of tabs just to take a quick peek at something. The only thing I don't like doing is having to right click on the mouse to access the feature via the context menu. Luckily you don't have to.
[alt+f12] opens peak definition on whatever type you happen to be on and [esc] closes the peek window again :-)
Here's a little more information on the feature if you don't know about it.... http://msdn.microsoft.com/en-us/library/dn160178.aspx