Craig's List (commonly written as craigslist) is an online classifieds system which allows free posting of unsolicited, passive, classified advertisements (similar to the classifieds section of a traditional newspaper, only you don't pay for the ad space).
It has received rave reviews and has an extremely large, loyal user base who use it to freely advertise all sorts of messages, from questions looking for recommendations of a good place to find products or services (i.e. "where can I take dance lessons in city X", or, "does anybody have accessory X for product Y? I've lost/broken mine and they don't make them anymore."), to giving away old or unused products, to offering up services (i.e. professional, sexual or otherwise).
Carpool and share your vehicle (or a seat) with friends, strangers, or just about anyone, to just about any location...
- Rideshare (NY example): http://newyork.craigslist.org/rid/
Yes, believe it or not some people actually share or temporarily/permanently swap their homes on Craigslist.
- HomeSwap (Tokyo example): http://tokyo.craigslist.jp/swp/
- wikipedia: Craigslist
- One Red Paper Clip: http://oneredpaperclip.blogspot.com/
- How to Upgrade an Old Phone into a Porsche: http://finance.yahoo.com/family-home/article/110125/how-to-upgrade-an-old-phone-into-a-porsche
- How to Swap Homes on Craigslist: http://www.ehow.com/how_2146709_swap-homes-craigslist.html
- Craigslist Breaks $1 Billion Mark: https://www.mediapost.com/publications/article/330737/craigslist-breaks-1-billion-mark.html