Meta-data, collaborative filtering and identity

Collaborative Filtering and Identity from John Udell. A use case we should be thinking about.

What if one would create a crawler application that, using all of these sources, could compine a complete “view” of my digital online self?
The problem though, is that “social” internet tools, that effectively visualize this stuff, are not all that common yet. Bloglines, Del.icio.us, and Flickr, and a few others, are still few and far between.
And then there is privacy. Now personally, I have no problem sharing all this metadata about myself. I would not even mind my browsing habbits being monitored to service the “social” metaspace like I do with the above-mentioned services, provided I had complete and transparent control over when what was monitored.
Wouldnt it be kinda creepy, once we indeed had a centralized match-and-compare system for all of this data, if you where to run into another person online that mirrored you and your interestes in every way? And online doppelganger, so to speak.