In my quest to find cool apps to download for my laptop, I ran across this gem. This app has one purpose, to keep your laptop awake when you close the lid. This is perfect for when you are downloading large files or watching a 2 hour long movie. It runs in the background and you can activate it just with a click in the menu bar.
https://code.google.com/p/macosx-nosleep-extension/
https://code.google.com/p/macosx-nosleep-extension/