Extra License is, I believe, an excellent niche forum. I see many general webmaster forums that offer "marketplaces" to buy and sell licenses, databases, sites, domains, etc. Many of these sites have additional requirements to post in those sections. So i decided to reverse that market and make a site dedicated to buying and selling of the previous mentioned items and have a general discussion section secondary. This allows, hopefully, a one stop shop for those in need of off loading extra licenses or acquiring new ones, all without the need to purchase a premium subscription or a minimum post count.
Having said that, please visit http://extralicense.com and let me know what you think. Thanks!!