Couldn't you make some application which scrapes Craigslist every 5 minutes and detects newly posted items, maybe filter them on some criteria, and SMS them to your phone?
The CL app can do that for you. Say, you save a search for "refrigerator" in a certain area, in the "Free" category, the app would notify you (it puts a # on the top bar of your phone) letting you know there's a new listing for "refrigerator". Same thing for "roommate" or "carpenter" jobs, etc.
It's pretty cool, wish I've known this app when I was looking for a free carpet.
Interestingly enough, just last month, I bought on CL and sold a pair of girl's snowboard boots for $15 more in a matter of 4 days. Mostly because I really didn't want it.I was just practicing on my selling skills. I'm more inspired after reading this.