Sadly Greenzap is a scam. Greenzap is the brainchild of known scammer Damon Westmoreland.
Greenzap was started in April of 2005, and has yet to deliver upon it's service. It merely takes in $100 from hopeful people thinking this is their ticket to get rich without working.
The $100 goes towards your paying in to the pyramid ponzi scheme. The people above you get paid a portion of your "upgrade fee" and in turn for you to make money, you have to convince multiple people to sign up under you and send in the "upgrade fee"
To date Greenzap has been banned from being used as a word in auction listing, most email systems classify their emails as spam, and the webcash is unspendable.
Their are no auctions, the "Storez" are commission junction and linkshare affiliates that are unaware that greenzap even exists (you have to make your purchases via credit card, the "merchants" do not accept greenzap as a form of payment)
The $50 is not cash, it is a fake currency that was created by greenzap to act as a rebate coupon towards a percentage of a purchase from their commission junction affiliates. The rebates can take longer than a month to be reflected in your account, and may not be honored at the discretion of greenzap. The rebates are less than the discount offered by going directly through the merchant.
Webcash has no value. A gift of it of $50wc of $5000wc ammounts to a gift of ZERO dollars. It is fake, and merely a way for greenzap to pay only a portion of the rebate back to you that you would have gotten by going through the merchant directly(keeping the rest for themselves)
go to google and search for "greenzap" and "scam"
They are currently also in the process of selling valueless "pump and dump" stock.
The "400,000" members are people that signed up thinking they would be getting $25 or $50 free, not until later did they find out that webcash is unspendable, valueless, and ammounts to a rebate coupon that is worse than the rebate offered by the actual seller.