I found this website. It's a way to search multiple cities within Craigslist at once as opposed to having to go back and choose each city individually and re-running your search.

http://www.craigshelper.com/

I've used it and it works fine. Plenty of room for improvement though from a navigation standpoint.

Another site I've heard of but have not tried is: http://crazedlist.org/index.cgi
This one may require Firefox to run - I'm not sure.

Happy hunting.