the only blockchain application (besides currency) i know of that lots of people use all the time is Steemit (you can use it for free without buying any digital currency, which makes it a great onboarding ramp into the blockchain space for new folks). apparently BitShares and Steemit are #1 and #2 for blockchain activity, which is amazing because you don't hear about either of them having scalability issues.
Supposedly steemit can handle hundreds of thousands of transactions per second. I don't know much about the technical details though but for sure steemit is one of the few gems out there.