I think a cool layer on top of this would be to create a P2P network where you can 'friend' certain peers and produce a reddit-like aggregation of new content from various sources.

- Friend another user by adding their key and IP to a trust group.

- When your client boots up, it connects to friend nodes and downloads their recent DHT.

- DHTs from all friends are summed to sort the hashes by descending frequency, perhaps with a time decay factor.

- Display reddit-like UI of content to User: see which files are recently most popular among the set of all your friends.

Possible improvements:

- User could customize time vs vote weighting, script custom sort rules

- Give certain peers greater vote weighting ('best friend' vs 'acquaintance')

- Allow peers to 'tag' hashes to create subreddit like collections of things.

- Allow attachment of metadata to hashes - title, description, etc - figuring out how to handle discrepancies between sources here could be tricky.

- Make client automatically re-host content in your DHT: hosting IS the upvote