It’s the oldest trick in the book when it comes to scamming: Play on people’s greed.
Take a look at a current one involving free iPads for beta testing :
The difficulty lies in telling whether a freebie giveaway is a scam sometimes. Some are scams, and some are supposedly real contests giving out free iPads, like the one here at freeipadgear.
When in doubt, it’s probably wise to reconsider: If it’s too good to be true, it probably is.