Right now is a good time to sign up for the Topbonus program from Airberlin. Between now and April 27, 2014, new members can score an easy 1,500 bonus miles. Simply for registering you will receive 1,000 bonus miles. You can earn an additional 500 miles for opting in to receive your communications via email and registering for the topbonus communication.
You can also earn extra topbonus miles for simple hotel reviews through HolidayCheck.com! You can complete a review in as little as 5 minutes to earn an extra 150 points per review.