A really interesting Firefox Add-on called "Glue" is being offered by a venture-funded company called AdaptiveBlue. (no relation whatsoever to my company, Gluejar, Inc.) Glue watches you browse the internet and when it sees you on one of a set of sites that it knows about, it reports the pages you're on to AdaptiveBlue, enabling them to construct a "Social Network of Things", where the Things might be Books, Music, Products, Wine, Companies, etc.
Overall there are over 300 sites that the Glue Add-on does something with. A lot goes on in Glue, and I didn't take the time to sort everything out. For example, when you go to a topic page in Wikipedia or a book page in WorldCat, or a stock page in Yahoo Finance, the url that you visited is reported to AdaptiveBlue. Usually, the Add-on then slides down a Glue header which tells you about what the Glue Social Network thinks about the Thing you are looking at. Personally, I find this very distracting, and I don't plan to continue using Glue, but I can imagine that many people will appreciate the consistent interface to the social network and other services that is presented. Other sites handled by glue include LibraryThing, Epicurious, Last.fm, ESPN, theStreet, ToysRUs, Expedia, GameSpy, Metacritic, WineLibrary, Flixster, Connotea, Flickr, Technorati, Walmart and eBay, just to name a few. It was very difficult to find the official list of sites that Glue works with on the GetGlue web site; I wish the AdaptiveBlue people were more upfront about exactly what they do on these sites. Nonetheless, the Add-on appears to do what it says it does. I also would like to see the user given more control over the sorts of things that are reported to AdaptiveBlue- I'm much more relaxed about sharing my Wine and Sports browsing than I am about my Wikipedia and Stocks browsing. And I really don't want to share my Russian XXX site browsing!
It's interesting to compare Glue to the OpenURL linking services that have been almost universally adopted in libraries. (I developed one of the first OpenURL link servers, which is now owned by OCLC, Inc.) Like Glue, the OpenURL link servers present users with relevant information and links to services surrounding "things" which are typically journal articles or books. One library that I worked with even used a social network to connect users to other users who had viewed the same item, just like Glue. There was even a Firefox Add-on developed that routed "thing" links to link servers. The link server vendor community worked with publishers closely to enable OpenURL linking; although AdaptiveBlue promotes its "SmartLinks", I doubt that many of the sites Glue is aware of understand what they are doing.
Given that AdaptiveBlue makes a big deal about the Semantic-ness of its technology, I was surprised to find out how it identifies "Things". The canonical way to identify a Thing on the semantic web is to give it a URI, and then attach properties to it. When I spoke with AdaptiveBlue founder and CEO Alex Iskold at the Semantic Technology Conference, he told me that they only use title and author strings to define book Things. In fact, they bundle these strings into keys (such as
books/cryptonomicon/neal_stephenson), then use the keys as if they identified a book, when in the real world, it's more complicated. So the "Things" in the AdaptiveGlue "Social Network of Things" are entities that do not correspond to books, but rather correspond to descriptions of books. Interestingly, this is exactly the approach taken in OpenURL URI's, which are really descriptive metadata packages, not entity URI's.
The first of Tim Berners-Lee's "Four Rules" for Linked Data is "Use URIs as names for things". Both Glue and OpenURL, which were designed separately as practical solutions for linking to things, seem to break this rule. Instead they build URIs using descriptions of the things, and don't bother naming the things themselves. Maybe Tim BL's first rule is wrong!