There's a small set of puzzles that are frustrating everyone's ingenuity lately: email spam, web spam, blog discovery, blog search, music discovery, and tagging generally. I propose that they share a common solution that will require a new Net application, which I'll call "crystal tags".
Surprisingly, the closest model for crystal tags is the antique NNTP network-news transfer protocol, substituting today's "tags" for yesterday's "newsgroups". With NNTP, local news servers cached all recent posts on every topic, and users subscribed to the topics that interested them, killfiling the authors they disliked. A session of newsreading in 'trn' was often as simple as pressing the spacebar repeatedly, which took you thru all new posts for all your topics, one by one.
But then the Web hit, and the content got buried in elaborate formatting. And with regard to efficient communication, our sights were lowered. (And whoever Google has assigned to replicating 'trn' via Ajax in Google Groups has so far blown the job entirely...)
RSS is a feeble step in the right direction, unhappily limiting its newsgroups to a single author.
The 'tags' part of "crystal tags" means that every user should be able to subscribe to any tags/newsgroups they like, and the application will help them find, track, and organise relevant content. If one user uses the tag 'mp3' and another uses 'mp3s' the application can handle this easily.
The 'crystal' part is harder to explain. It means that over time everyone's tags should crystallise into a dynamic unity, where everything that should be synched, is quickly synched.
Synching in NNTP required two news servers to connect and compare which articles each had, using unique article-numbers, and to fill each others' gaps.
With crystal tags, you'll get to choose who you synch with, and to what degree. Someone whose judgment you respect, in a given area, will get synched automatically, and someone unknown will get synched only tentatively.
The webpages you publish will be (as now) available to any random stranger, but once ip-number and/or passwords have established a known identity, personalised or private content can also be offered. Your public blog will (as now) display links to new content you recommend to everyone.
MP3 blogs will offer playlists that add new discoveries at the top, and can be linked and subscribed-to like other tagged content, but also played.
Email will follow the same patterns, except that strangers can make 'cold calls' that may or may not get read by the human being approached. If these are followups to public blog posts on a particular topic, it should be clearly stated under what terms they can be published.
Somehow given topic/tag/newsgroups will get associated with particular hosts, who will be responsible for filtering submissions for spam, vandalism, griefing, etc.
Some sort of ping-system should be built-in so that checking for new content is a minimal effort.