Hey jsankey, the advantage of Curbit is simplicity. All existing solutions require a fair amount of effort of the person wanting to get rid of something. Freecycle is solving the exact same issue, but I feel that the burden that comes from having to manage pickup / messaging / condition reports all from a very rough web UI deters a huge portion of the population. We shouldn't have to work to get rid of something for free :)
Compared to classifieds in general, it can be much simpler to use, because money isn't changing hands.
Compared to classifieds in general, it can be much simpler to use, because money isn't changing hands.