www.audiencerewards.com - by answering a few questions about Broadway shows, you can earn 2 miles per answer for United and for US Airways.

Also an EXCELLENT way to earn a few STARWOOD PREFERRED GUEST points, and extend expiration by 12 months.

Points to SPG seem to take around 2 weeks from when you answer the questions to appear on your SPG account.

Points can be earned for Delta (no expiration of miles) and Amtrak (but will NOT extend expiration - you must "ride them rails" to keep AGR points from expiring)

A thread with answers to current questions:
http://www.flyertalk.com/forum/miles...-s-air-49.html