Reputation data is a specific and interesting case, because its value goes way beyond the simple reuse of purchase history. Here, if someone uses their eBay reputation to estalish a reputation elsewhere, then the origin must be authenticated.

To a lesser extent, one will have to be very careful about scams based on any kind of data retrieved from commercial sites, and qhared with others.

Building a system that brings value and is trusted by all promises to be a lot of fun!