Fansite Prometheus-Movie.com is doing another one of their competitions where you can win quite a bit of stuff. One lucky person will get a copy of Prometheus on Bluray, two posters, Aliens Infestation on DS and the Aliens Omnibus comic.
Go to their competition page, read the instructions and answer the four Prometheus-related questions. The competition closes on November 25th and one winner will be drawn at random. I assume there are no location restrictions.