Know of any features or tips and tricks in OS X 10.7 (Lion)? Kind of like this: Please share your hidden macOS features or tips and tricks but specific to OS X Lion 10.7.x ONLY

Do you know any hidden or little-known nice feature of OS X 10.7 (Lion)? It doesn't matter what it is&mdash;maybe just a short terminal command. Share your experiences on hidden OS X features here.

Please post one tip per answer. Please also check to see if your answer has already been posted - duplicate answers will be deleted. To search the answers of this question you can use inquestion:18677 (or inquestion:this, directly from the question page) in addition to your search terms in the search box in the upper right hand corner of this page. 

Also provide details on how to achieve that feature, and if possible, include a relevant image too!
Holding ⇧ and/or ⌥ while resizing a window retains the aspect ratio and/or anchors the windows center, respectively.