I posted this link a few months back, noting how it doesnt specifically say how many miles you get.
I can now verify that i recieved 15,000 as a signup bonus, and did not get charged any annual fee.
You can keep signing up for this every 3 months, so what are you waiting for, thats a free trip to kangaroo country in 1 years time!
united cc linky
do you have to cancel also every 3 monts ( or only sign up again?
i believe that you do not need to cancel