Revenue streams are interesting to consider with these sharing focused start-ups. If the values of these users shift to "collaborative consumption", does that decrease or raise questions with advertising as a source of revenue (ethically or effectively)? It seems that a possible underlying value of these ideals is less (or anti) consumerism. Would these users be more open to a 'fee for service' model? (That would be refreshing.)

Side note: Profounder.com is another example of a social lending platform that does not require a fee.