links is a beta project of the Yale Center for Medical Informatics and the Yale University Library. It is a group linklog: you can post on it the links you are reading and look at what other people and groups of people are reading on the web.
You have to get a Yale account to log in and add your bookmarks. links lets Yale patrons create and join groups, too (groups are sets of people with some shared interest: a course project team, a research unit or some friends…).
You can also syndicate your own links or your group links using RSS, or export the whole set in such a wide number of formats: by now at least the XBEL, XOBIS and MODS.
Either, you can take a look at links with your cell phone thanks to PDA view offered at the bottom of the pages, along with the orange buttons of metadata formats. You can also look at people creating records in links and view the words they tagged resources with.
Tags are listed alphabetically in an apposite page: you can browse them and pick up the one you are interested in with all the records displaying link description, user (and/or group) details, date of record issue and – if in case of open archives – eventually the name of the repository in which the resource has been submitted.
But… improvements are going on – at links they say: "Our goal is to make links an extremely useful and easy way to share information or just keep notes for yourself. Over the next few months we will be working to improve how links can keep more detailed information about your links, such as bibliographic fields for journal articles".