These are not merely rhetorical questions; they refer to the BookCrossing phenomenon.

One of BookCrossing's taglines is "generosity is addictive" - another is "more like giving, less like keeping."  What we are seeing here is an enjoyable and scalable way of building social capital. Moreover, all of this sharing is mediated through a web site.  All of us who care about how nonprofit and philanthropic organizations go online to help achieve their missions need to learn lessons from the BookCrossing community.