Cimorene

I have been using delicious for my bookmarks since 2006, but using it for recs for a bit longer than that. It has become much more widespread in fandom within that time period, and the more it grows and networks, the more useful it is as a source of recs.

I'm surprised you missed the 'social bookmarking' aspect of it; I think it's part of the boilerplate copy around their site.

And, again, I'm well aware that some people don't wish to use it socially, I agree that that is valid, and I don't need or want to discuss that aspect of it.