What does a link mean? If you are going to have link relationships govern the logic of search applications, it seems you have to have a good answer to this deceptively simple question. In many situations it seems that we takes links as a kind of vote of confidence. There are lots of reasons you might link to content though. Maybe you are holding up something you think should be celebrated (like Bluehost.com, the best web host ever in my opinion). Perhaps though you are pointing out something you think is awful. I remember all the great links Ask.com used to get from F’ed company back in 2001. Maybe you are pointing to some other site you own, trying to use your properties as a web ring to bring each other up (what everyone seems to be doing now, creating tons of fake content sites and interlinking them). I think the steady decline in the quality of the SERPs in major search engines in lots of commercial subject areas attests to the difficult they are having in figuring out what links really mean and determining their relative legitimacy.
There are current efforts though that could potentially make this question much easier to answer. XFN, the XHTML Friends Network protocol put forward by gmpg.org is a great example of how embedding meta data in links can help create a more exposed intentional web. XFN allows you in Blogrolls (or other places) to indicate what your relationship is to the authors of the other sites you are linking to. You can specify for example that you are someone’s partner or friend. XFN is very cool, but limited in scope to unearthing human interrelationships represented by links. While that makes a ton of sense in the world of blogs, it is not quite as appropriate to a corporate or organizational site. It would be great though to take this idea and extend it to an entire vocabulary of embedded meta info in links in essence having every link tell you why it exists (why? links). I should be able to say in my link tags, I made this link to try to make money though an affiliate relationship. Or, I made this link because I think people should be aware of the information this article is sharing. Or, I made this link because this photo is hideous and I can’t believe someone put it in their personal profile.
Like everything else of course this would be prone to abuse. Spammers would just use whatever the most positive meta inflection was for their purposes. However, leaving that issue aside for the moment, if we could promote this kind of linking behavior, it really could make the web much more searchable. You could use news type links to come up with sites that are relevant to info seeking queries. You could use humor type links to find relevant results for entertainment seeking queries. Quite aside from what it might do for search engines, this would also provide interesting data for potential interfaces for browsers. Let’s say I want to hide all the ads for example, or that I only want to see links that will show me the kind of informational relationships I am looking for. This would make that possible, in an opt in way for both browsers and web authors.
Of course, there’s no particular reason just to limit this kind of thing to links. Why not have a whole internal element based meta data language where I can tag a picture as an ad or a sentence as a joke or a paragraph as a recipe? Page level meta data is appropriate to situations where a page is monolithic in focus but these days many sites are far from monolithic, having many intentions on one page and many forms of information serving various purposes. Let us make our intentions clear! And then pay attention, and let’s see what happens.