I need your iPhone 3GS serial number

Nice try..there is zero incentive for me to email you my phone's serial number, and a possibility (even if remote) that giving it to you might come back to bite me.

I checked the risk/reward ratio, and came up with a number that approaches infinity, so I'm not real sure how to break the news to you, but ummm you cannot have my iphone 3GS serial number

Depending on how sequential the serial numbers are, the answer (the probable range of serials) can probably be derived either from people reporting true serial + some random noise offset (of known distribution), or maybe through some zero-knowledge protocol (but I don't know if zero-knowledge proofs are practical on a many-party scale).

Nope, not going to happen.

"Just email it to me."

For the love of science, put a textbox and a submit button, and let the gnomes do their job.

http://www.wufoo.com

don't ever give out the serial number of anything you own. it's too easy for a scam artist to report that it was stolen, and now you have to answer to the police and prove you own it.