Many expired domain names have traffic that comes with them accumulated by the previous owner. And you can use this to your benefit. By pointing the domain to a parking page or your own site, you get this "expired traffic" for yourself!
You can sell your expired domain name. There are lots of places to sell a domain name, a portion are listed below:
http://www.sedo.com
http://www.afternic.com
http://www.namepros.com
http://www.domainstate.com
You can develop a site for your domain name and earn advertising revenue with programs like Adsense.
Thousands of valuable domain names are expiring every day.
Get free expired domain name lists daily at http://domainslist.blogspot.com