Well... I'm not going to. Asking this question just for the fun of it. If you're a very experience coder with good web development skills, what do you think about creating a website that will compete against craigslist.org.
People who use Craigslist mostly utilize it for advertising services or goods in their local communities or nearby areas (e.g. towns). Most CL users don't like to ship their items or are skeptical about accepting Paypal as payment method. Plus Craigslist has updated some of its site's features in past few months it could still stand to make further improvements. There's already Gumtree, OLX, oodle and eBay classifieds competing against Craigslist. I'd develop an Android mobile app to compete against what Craigslist currently offers its community of users.
It's not exactly a terrible idea, but the internet is already kind of full of Craiglist clones. Of course that I would do it — at the right time, with the right marketing plan.