These are three sites that you must know about if you want to sell a product or service locally:

• Craigslist.org - the 600LB gorilla of classified ads, you can list products and services for sale here, extremely high traffic
• Upcoming.org - List upcoming events, seminars, happenings here for free, just purchased by Yahoo so traffic is sure to increase
• Google Base - List things for sale on google, kind of like classifieds ala craigs list, but this will get indexed and show up in google search results if relevant

Just remember as well, even if you don’t sell anything, any link back to your web site is a good thing!