There are several levels of what's going on: first, with the economy going downhill, people aren't showing up at their usual sources of disinformation, and advertisers want to reach them. Odd as it sounds, this is the harmless version of what's going on: they're subsidizing something in an effort to build a mailing list, or "e-mailing" list. You may notice that suddenly your inbox gets lots of stuff you didn't anticipate: that list of addresses can be sold and re-sold to other advertisers, and they're happy to give you a try. You might even agree that it's harmless until your inbox reaches the stratosphere: "You have mail" turns out to mean another 300. Since this morning. It's another way to realize that your time has value, and that perhaps that offer wasn't as good as you thought it was.
Second, service providers have noticed that you're paying something, shipping costs, and giving them a credit card. You will find that some of these have authorizations to charge your credit card money each month for the privilege of access to their information. Some credit card companies are sharp enough to catch these, and will notify you at the first statement -- but most won't. As a matter of fairness, they will give you a difficult to execute procedure for canceling the ongoing charge (calling an 800 number that rings 50 times only to yield to a voice advising you, in Spanish, that the mailbox is full is one I've seen). Some of these will involve making a "support request" at an associated website: and they can always say they didn't get it. It really doesn't improve when whatever you ordered arrives: you've just validated a mailing address, and you're back on the solicitation lists you thought you were off of, and there will be a notice inside detailing one of the barely-working methods of canceling the account. Slimier, arguably providing service for value, but not in my book.
Some sites are offering premiums like laptops -- but only if you recommend ten friends. And this leads to the noise in the equation: if you want the laptop, and you provide ten friends, you're engaging in the same kind of thing that the post office used to ban as "chain letter fraud". It doesn't take too many levels of "refer 10 people" to exceed the population of the country. So something interesting has developed: a market in "being a friend" for referral purposes. There are websites dedicated to posting the offers and allowing acceptances for groups of temporary friends, all of whom agree to fill out the information on the site, pay shipping, and otherwise look like a genuine referral in return for cash. The poster gets the laptop, or xbox, or whatever premium the site offers, (note that paying 10 people $20 each not only covers their shipping costs and gives them walking around money, but also gets you a laptop for $200 -- not bad.), and friend-for-pay cancels the service after ten days or so to look like s/he meant to check out their service and changed his/er mind.
This "noise" has another name: fraud. The friend-for-pay is engaging in a conspiracy to defraud the marketer of the benefits of his scheme for getting his valuable address list by helping clutter it up with unmarketable junk, and sending off laptops to people who haven't cooperated in good faith. I'm sure the FTC, or Department of Consumer Affairs or some other local government entity, is starting to look out for some of these things (and I'm sure that Google and other companies that engage in giveaways should be more interested in their bottom line). If they aren't, of course, just pass this on. I'll pay shipping.... (OK, kidding)