I've been a longtime user of Craigslist. I got my San Francisco Apartment using it, bought a few things, and eventually I met Craig and we've talked at conferences together about what it takes to run a community. At the recent SXSW fest, a panel redesigned Craigslist. It's a definite improvement and it looks fantastic (they redesigned the listing pages as well). Other designers took a crack at a craigslist redo that was closer to the original.
The one thing I really didn't like about the SXSW Craigslist redo is that the top bar is all wrong. The dark color pushes it back for me, in a banner-blindness sort of way. I didn't notice it at all for the first minute I looked at the new site. Then I thought about how I use Craigslist, and I'm a big searcher. I either search from the front page, or I dive into the appropriate Sale/Wanted section and search there. I know the tech behind Craigslist is pretty simple and they're not much of a search/IT company, but I would love it if they surfaced search in such a way.
So I redid it. Here is the full size version. I took a screenshot of the redesign and moved stuff around in Photoshop to my liking. It's obviously a very Google-like redesign, but then that's how I use Craigslist. I could picture the Craigslist subpages carrying the search at the top just like a Google result page (just the top 100px or so), so this theme could be continued throughout the site.