I’ve been in the online ad game selling space to sites like this, tickle, get an ipod for filling out this survey & other of these types of sites & I’d say that 95% of what I saw was just a crappy lead generation deal to get your email or physical address so they can say they have a mailer with xyz demographics which they manipulate anyway. Then all of a sudden your mail box at home or on the computer starts filling up with junk.
I’d say stay away unless you know someone who works for that company that you can trust.