I looked at the links for this exercise and settled on NLC's Reference Department account. I picked astronomy as a tag and then "Your Sky" as a website. This particular one has been "saved by 283 other people." The comments about the site were similiar--some were almost identical. One comment caught my eye as hinting about the sharing aspect of this technology: "If I have your mailing address, you'll soon find out why I'm looking at this site." That seems to be the main point here.
I found the tags similiar and ranged from 1-9 per person--the common tags accounting for the sharing of info, linking people in their search. One thing of note: the 283 people were from different countries--an international chat!
Obviously, this opens one up to a lot of info. One problem I see is that a lot of it is opinion. Where's the documentaion? Where's the bona fides? I suppose after a while one gets a sense for this. With experience you trust certain sources and become your own gatekeeper. This ties in with the other problem I see: it still seems like a flood, a data deluge. I gather Del.icio.us is supposed to be the answer to that but it is not appearant to me just how.