Roomer is doing for hotel rooms what Airbnb did for your very own home. According to the startup, which has just raised $5 million in Series A led by Disruptive, there are 81 million hotel room cancellations in the United States every year. Roomer tries to solve that problem by letting users sell their unwanted hotel room, which would otherwise cost a cancellation fee, at a discounted price. For the user, they avoid paying money for the unwanted room (and they might even make a few bucks), while the hotel makes far more money than they would from a cancellation fee from incidentals like WiFi, minibar, etc. Roomer sets up through hotels and travel agencies directly, so that each time a user wants to cancel their hotel room, they’re sent to the Roomer site to list it for sale. Roomer handles everything from marketing to reservation transfer to payment out to you, all from simply sending the hotel confirmation email to the service. The user gets all this for free, and then pays ou...