I've seen more than a few invitations to join Greenzap. While I have considered it (hey, even paypal paid you to join when they started up!), I also have to think back over my time online.
There was a time when I was determined to make a living off of my online time. Paid email, pay to surf, pay per click, you name it, I did it. While I did make money off of a minority of those companies, the majority were scams. Either the payout limit was so high that you could never hope to reach it at their pay rates, or once you DID reach the payout point, they accused you of cheating and took away all your points (Cashfiesta was the one that did that, for anyone who ever considered using THAT scam; after I got burned, I checked message boards and found it was common practice for them). In essence, what they are doing is fraudulent, and is a theft of your time and resources.
Now enter Greenzap. While I have seen it mentioned many times, I saw for the first time today a site that questioned their credibility. Unfortunately, it didn't load properly, and I couldn't read the text. But I'm inclined to remember the old maxim, "if it sounds too good to be true..."
At worst, I'll be left short $25 I could have had. AT the least that will be one less company out of the 5 billion that already have my personal info.