The sad thing is that it would be quite easy to drastically improve Craigslist. First, a simple CSS and design cleanup like this one: http://www.wired.com/images/article/magazine/1709/ff_craigsl...

No drastic changes, just a cleanup. Then you add an advanced search tool with maps and filtering based on some criterias like distance and price.

Then there's issue of spam. Solve these three issues, and CL is basically "fixed".