I've started a petition asks eBay to require serial numbers in its listing for bike frames / bicycles (inspired by a similar one directed at eBay UK).
Could you help spread the word and sign it?
Note: This is a work-in-progress, and I've been getting lots of helpful feedback already. For frames without serial numbers (custom, illegible, Nashbar, etc.), ideally there'll be an option to denote this with an explanation.