I'm not sure how this party Steem applications will develop but I have no doubt that they will.

Here are a few examples of sites can run better on Steem: https://steemit.com/ecommerce/@manipulable/steem-to-the-moon-top-ten-use-cases-beyond-steemit-com-and-beyond-a-ponzi

The example I think related to you is Airbnb/CouchSurfing. If you were able to create a kind of Slock.it for Airbnb that does not process payments, and instead sells these app-controlled locks (whether through a smart contract or not), you could basically decentralise house sharing and make it easy more convenient!

To prevent people reviewing places they haven't stayed the lock could be connected to the website in some manner, so opening the door triggers your ability to review.

Here is the problem though... Let's say i am a high Power individual who stays in someone's house and then leaves a review. At the same time I comment on a blog post here on Steemit. The value of the review is much more than that of the comment, but to far fewer people. How will Steem balance the rewards in a world of multiple Steem apps that require different incentive structures and offer different values propositions.

I have a few thoughts on that and I'll be posting soon as things become more clear. I haven't received responses from anyone in the Steem dev community.