I had signed on for USAir a couple of years ago, and had 500 miles sitting there for signing up. I just got the same deal in the mail--5 subscriptions, some being some very pricey magazines!
It makes me wonder (wheels turning as I type) if I shouldn't go ahead and register for one or two programs a year, take the 500 - 1000 miles for signing up, and wait for the magazine offers in a year or two...
JP