Review my Craigslist killer
sonink: I think before you want to make something like a CL killer, you first need to understand what is CL, why is that so popular as it is -  essentially what is the primary driver of business for CL.As other would have already commented, it seems that the simple interface is one of hte biggest drivers for CL. You would find the same if you dig through tons of forbes/media articles. I think that is not the case. That is just post-facto insight - something which gets generated a lot in the media.The primary driver of business for CL afaik is data and the people who already use CL. If I want to sell something I go to CL because it offers me  the most amount of buyers. If I want to buy something vice-versa. It is a self-fulfilling loop.The only way to beat CL is to figure out how do you overtake CL in its primary driver of business. It will not be easy - I dont know even if it is possible. But what I do know is that anything else (neat UI, AJAX) is just inconsequential.