Of course, Your email (and a real address for shipping) is collected - a nice little spammers database!
Maybe, just MAYBE, it might pay for a few, with the incentivised clickthroughs (that would also pay points at the RPOINTS forum)
http://www.rpoints.com/?ruid=24242 MY referral - join through a referral link, both you and the referrerer get a 500 point (£5) bonus when you reach £25 (2500 points) ... from shopping rebates, free comparison site points, joinup points (a LOT of DVD rental free trial points). Skip the referral, no bonus for anyone
Rpoints is the most open and honest reward scheme around, though there are a couple of similar points sites.
Maybe I'm breaking a confidence here, but if you make it to £50 you can go "VIP" and get an Amazon discount (on using your points). I got VIP with NO referrals, and with only one rebate, the rest was free points, though I did push the max limits, and there was one more good freepoints site worth 20 per day
Otherwise, you can cash points in at £10 or above.