Vudu has no signup or monthly fees and gives signup freebies.
Vudu (a part of Wal-Mart) offers a similar selection of movies at a choice of streaming speeds from SD ($4) up to eye-popping XHD with 5.1 DD sound ($6) with HD in the middle. This is comparable to Amazon Prime, but no "free shipping". Plus, you get a $5.99 credit for each device you register with them.
So, no sign-up fee, no monthly charge, great PQ, prices comparable to Amazon, and a $6 credit for signing up.
FWIW, we've got both but we do enough ordering from Amazon to justify belonging to AP purely for the free shipping.