My only compliant is categories and searching.

For example my side hobby is old Volkswagens. Since they have no way to categorize vehicles that are for sale, I have a few bookmarks with crazy search strings. VW + (1951|1952|1953.. etc)

Add to that fact that you can only search one section of craigslist at a time, I have crazy search string bookmarks for like 5 sections of craigslist. I'd like to see a craigslist central where my searches span states and regions.

Other then that I love the dead simple UI and no ads.