Localocracy has a nice way of expanding into new communities.  They avoid the “tumbleweeds” problem by building support for the initiative before it starts, in a kickstarter-ish sort of way.  This is, of course, not a new idea, but I think Localocracy does a nice job of executing on it.  E-Democracy has long used a similar system for building interest before groups launch.  It’s also reminiscent of the genius way that Threadless builds demand for t-shirts before deciding to print them.  I like the way that Localocracy uses the approach to both build excitement and guarantee some level of engagement once the sites go live.