Lufthansa is currently offering 300 bonus Miles & More miles for downloading their new Miles & More app and linking it to your Facebook:
With the new Miles & More app, ‘my Miles & More’, members can connect the worlds of Facebook and Miles & More for the first time. In the beta test phase we want to give users the opportunity to get to know the system and to point out any necessary final adjustments to us. We will give 300 award miles to all the dedicated testers: once you have registered and have connected your own Miles & More account, you can start.
This isn’t very time consuming at all, so is an easy 300 miles. It’s worth noting, however, that you must have an existing mileage balance with Miles & More in order to be able to take advantage of this.
(Tip of the hat to Malta Points)