Mark Mearin, the Director of Online Real Estate for DotVentures, LLC and works with other top domainers to help them develop valuable online real estate, by taking a nice keyword domain and linking it to a tool that allows you to turn up the value on a domain name and increase its value exponentially.  Mark tells Domain Investing that; "Hey, domain names are great and all that.  But if you can't unload them when you have other opportunities, taking some nice profit, then whats the point?"  I talk to guys all the time that think they have the greatest name, but I ask them what my buyers are going to ask them...."how much organic traffic or natural traffic do you have"  Otherwise its just opinion.  And you know what they say?  Check out his domain investing blog page.