How-to wake-up a MacBook [Pro] that doesn’t want to?
On my desk I have a set-up where my previous MacBook and my actual MacBook Pro are used closed, displaying on external 24in LCD with an alu keyboard and gamer mouse connected to my USB hub.
To start, I have to open my MacBook Pro, start it, then at any point, close the lid to put it to sleep, and wake-it up by pressing enter on the keyboard. It enables me to have a clean desk, or nearly 
But sometime my MacBook Pro doesn’t wake-up when I press enter or click on my mouse, wether they are connected to my USB HUB or directly on any laptop USB port. It annoyed me until I found a workaround that seems to work any time: I plug an USB key or any USB device on the USB hub or on the available USB port of the MacBook, and then it wake-up instantly!
PS: If you put an USB key, you just have to insert it, and when hearing the Superdrive sound, remove it, it wont even mount.