Here's one for users of the Inception App on the iPhone.
If you look in the Game Center for the achievements for this app there is one listed called "The Kick".
Here's one way to unlock this.
First, put the phone face up on a soft but firm surface, like a carpet or mattress, in a quiet place. It probably helps if you have the phone's power plugged in, so it won't go to sleep. Open the app and go into the dreamspace - it should go into the "Quiet" dreamspace. If not, make sure you are in a quiet area and are being still!
Then, just wait. After about five minutes you'll hear the Inception signature tune kick in, which will end with six "PAAAARPP!"s.
Watch the screen - you will see the Infinity symbol vanish briefly. This is your cue to take the Kick.
At this point, pick the iPhone up and drop it, from about 12 inches, onto its back.
You should then see the "Kick" screen:
This allows you to take a picture using the front or back camera, which you can then email, add to twitter or send to facebook. The picture you send will say "I've discovered the kick! http://inceptiontheapp.com" in the corner.
Unfortunately it does not seem to unlock anything else on the map, but it does change the "Induce dreamworld" button from red to yellow.
You can also get the Kick in other dreamscapes - I first found it in the Action dream, but it is difficult to reproduce. Basically, just wait for the "PAAARP!"s, wait for the infinity symbol to vanish, then "drop" the phone (carefully!).