Definitely agree with the decentralized market idea where anyone can perform the service. But, alternatively, an opensource version of steemvoter might work as well.
Delegation upvote services might be the key. Nobody spends money and various small communities benefit within their topic/tag or something.
Your decentralized trending tabs thing is taking a little time for my mind to wrap around.
I like the reputation aspect. One thing that frustrates me about reputation is that it holds virtually no value at all. Its just a number next to our face that suggests we either have a ton of SP, spend a lot of bid bots, or rarely get downvoted. The last part is good, but the first two nullify the last's value add.
Determining reputation and trust is the core fundamental problem of every blockchain in existence. Blockchain needs more consensus algorithms. proof-of-brain needs one most of all.