Well worn territory here. I've been part in a handful of discussions with the wizards behind the Hubski curtain about such things. I think one issue is that multiple tagging might start to dilute the content. There was talk at some point of allowing users to tag others content that they've decided to share (or re-post). Say you like an article, you click the hubwheel and there appears a text box that allows you to add a tag. This way, individuals and tags are linked together. And then I'll know that aeontech is the one who keeps tagging all my posts a particular way and shedding them in a certain light. I think the major speed bump to this moving forward is that there is not so much of an incentive for people to be proactive on ad-tagging. Plus I think the coding is a bit of a nightmare. For me, I like the kind of immediate living breathing aspect of my feed which is why I tag very little. And if I miss something, tomorrow is a new day.