When an opportunity to move to a new city landed in my lap, I found myself on Craigslist multiple times a day looking for a new apartment in a new city, looking for renters to take over my current apartment, and looking for poor souls to shlep my used IKEA furniture on to.
And while Craigslist's interface is often described as "fine for what it is", having to look at that site multiple times a day for an extended period of time is enough for someone to try to make it better, even if it's just for fun. I focused on enhancing and modernizing the experience by simplifying the core pages while keeping the interface familiar and in the same spirit as the original.