I like this idea of using tags instead of distinct boards. I don't know if there should be a limit to the tags. People could vote on tags, the more votes a tag has the higher the score / weight of terms in search.

Maybe there could be some sort of content curation feature, create themed channels that consist of posts that you create or add to favorites. People could subscribe to either a user's channel or the user altogether. The difference would be that by subscribing to a user you could choose to subscribe to everything they post and/or every channel of theirs.

Just some things off the top of my head, would like to know what other people think.

Great thoughts. I love the idea of community voted tags. I don't believe there should be a limit to tags. As content ages, people will continue to annotate the metadata. You're right, there must be a mechanism to prevent tag spam. There will also be collusion among users to form brigades in an attempt to enforce their viewpoint on others. In my opinion this is a serious issue with community tagging.

There are possible solutions to this issue. Ultimately, I think almost all of them would require modeling a tag's score.

Some random thoughts include weighting a user's tag with their log-odds probability that they will tag it. e.g. A user named Eve has a known history of brigading (computed from the public ledger) or mistagging (other users generally disagree with Eve's tags) then their submission to influence a tag's score will be appropriately down-weighted. This might be difficult to evaluate, but is worth considering.

I love the idea of subscribing to tags! This is a little more like Stack Overflow, where content might have any number of a group of tags, and interesting things can be discovered via the cross-pollination of something new coming across a tag because the community identified a new "topic".