i wonder whether there is enough interest to build a community-supported "open-craigslist" on top of which anyone might build their own tools/services.
The second comment on this thread that suggests that the problem is "building an open replacement". Have you been on Craiglist lately?
You could try to replace Craigslist using only variants of the code shown in the original Rails screencast, with no consultation allowed. But you'd fail, because the result would be (from a UX perspective) better than Craigslist.
When people find a forum in which to post classifieds, they have exactly one (1) overriding goal: find the forum with the most vibrant market. There are a million zillion little things Craigslist can do better, but they are unlikely to make a big impact on that (1) goal, because Craigslist is already so vibrant that it has mostly put the rest of the classifieds "industry" (ie: newspapers) out of business.
You can disrupt Craigslist vertical by vertical, same as with eBay (before they became totally crap) and Amazon (even today).
There is really very little in common between renting or selling a house (which Craigslist is only good for in SF/SFBA, and ok in some college or other major-metro markets), selling small, highly standardized items (used iPhone 4s), selling used cars, dating or prostitution, and selling sofas. The unprofitable ghetto is selling sofas, and craigslist is the right place for that.
Amazon marketplace utterly destroys craigslist for selling most standardized, current-production items (books, electronics). There are Apple specific marketplaces for used Apple stuff which are by far the best. Etc.
Mostly because their interfaces are even EASIER for buyers than Craigslist. When I buy a used book from Amazon, it's zero friction, includes all the reviews for the new book, and has a single-button to buy (using stored payment, and shipping info, and shipping in 1-2 days for free).
I thought about adding something like this to my comment, but you said it better.
In essence, the way to take market share from Craigslist is to take any market Craigslist dominates, and reimagine it as something other than "classified ads". It seems like you have to compete with the whole concept of "classifieds", not Craiglist.
i meant it not as a way of solving the current problem so much as a way of preventing it from happening again. indeed, i haven't any great ideas about how to redirect the massive momentum that craigslist has right now.
