Always thought the lowly bookmark is an overlooked gem. Delicous.com has its moments but failed to get lift off after changing hands several times. ChannelKit may prove easier to use and so more successful in its Metcalfe network valuation (Metcalfe's law is value of a network is squar its members). Perhaps Channelkit can go where Delicious looked like it would but never quite made it.
Why is bookmarking relevant?
One way to create meaningful tagging is to "normalize" via scale. When a LOT of people all tag, share and publish similar content norms and patterns emerge. What you call email mkt I might call email marketing, but as we see aggregate numbers that feedback loop can help bring outliers into the fold.
If email mkt has 10 tags and email marketing 10,000 tags chances of the outlier being brought into the "email marketing" fold are good. This kind of massive data manipulation at scale can manage larger datasets faster and cheaper than trying to have a team do it.
As a crowd works their bookmarking the data smooths out, outliers become easier to identify and the backend tagging influences the front end consumption creating a self reinforcing feedback loop (gets more efficient as scale increases creating the much sought after "get more with less" ideal).
The web's secret is always some form of crowdsourcing or crowdfunding since the impact of anything at massive scale creates meaning and patterns faster and so lowers costs and increases profits. The key is getting out past the "breakers" of Metcalfe's law (i.e. hitting scale numbers that are turning over faster and faster because use of the tool is self reinforcing and beneficial).
Via Ana Cristina Pratas, Martin (Marty) Smith, Mark E. Deschaine Ph.D.