go to this site http://www.gaming.lagoon.com/?ref=366701 (without dot in between) and fill out offers to get enough points. once u get 8 points(doesn't take long) select runescape membership as ur prize and they will email u the code.
Hey if u want a to be a member for free go to http://www.prize.rebel.com/index.php?r=675520 (without dot inbetween prize and rebel) sign up and then do offers until u get up to 10 points then buy the ultimate game card. this actually works :D