[update 10/22/13: I failed to mention that the promotion is only valid in the following fare classes: A, J, C, D, Z, P, Y, B, M, E, U, H, Q, V, W and S. If you're planning to take advantage of this promotion, be sure your fare qualifies before booking.]
I don't typically write about airline promotions since they tend to be either targeted to certain customers or valid only on certain routes. However, there's currently a United Airlines promotion that doesn't appear to be targeted and that everyone should register for immediately.
Under this promotion, you'll earn double redeemable (not Elite Qualification) Mileage Plus miles on all flights operated by United or United Express within the continental United States between October 21 and November 21, 2013. Unfortunately, you'll only earn the bonus miles on flights you book during the promotional period, not existing reservations.
If you're flying United in the next month this is an incredible promotion, and if you're planning to mileage run for status before the end of the year, it's definitely worth scheduling your run during the promotional period. Register now, before you forget.