Points can be used for flights on any airline, and there are no blackout dates. (creditdonkey.com)
1 point for every dollar spent on eligible purchases; book flights on any airline without blackout dates or seat restrictions. (creditcards.com)
These services are very straightforward: you earn miles for each flight you take, and when you accumulate enough, you can redeem those miles for a free flight on that airline. (lifehacker.com)