Based on little I'm thinking "it's Skype, but for data" where the service is driven by free point-to-point file transfer, but related buffering/storage or other

Based on little I'm thinking "it's Skype, but for data" where the service is driven by free point-to-point file transfer, but related buffering/storage or other "hey that's great but I'd pay for..." services tacked on (like Skype's X-to-phone paid services - dirt cheap, but cumulative).