Treat the hyperlinks in web pages as "votes" for other web pages. Then use a feedback loop so that pages which receive more votes from others have their own votes become more powerful. That's how the PageRank algorithm pushes the best pages to the top of Google search results. Twelve years after Larry Page and Sergey Brin published the initial description of PageRank, Google says it still serves as the core of its technology.
So if hyperlinks are votes, how do we make sure the electorate uses their power wisely?
For one, we need to ensure that people only vote in their own name. Not so long ago, that ideal was effectively violated by blog spam. Automated programs would comb the web looking for any blog where they could post hyperlinks to the likes of Viagara sales. Successfully adding such a hyperlink on a well-known blog would result in a strong PageRank "vote" for the spammer's page. So in effect, the spammer was voting in the blog owner's name (and hijacking his PageRank strength).
This issue was largely fixed in 2005, when Google announced that it would start interpreting a rel="nofollow" hyperlink attribute as a request for exclusion from PageRank calculations. Blog spam can still be a problem, but since most blogging software now adds the rel="nofollow" attribute to hyperlinks in comments, it won't benefit spammers' PageRank standings.
But is just being able to mark a hyperlink as a "non vote" enough? Wouldn't it be nice to have even more control, such as specifying which hyperlinks are positive votes for the referenced page and which are negative votes? That's what some of the Technorati folks are aiming to allow with the Vote Links microformat. It proposes rev="vote-for", rev="vote-abstain", and rev="vote-against" attributes to allow page authors to express their voting intents for each hyperlink.
Still, is even that enough? I wonder why there is no effort to allow authors to control the relative strength of their votes. The Vote Links FAQ has an entry covering this, saying:
Q: Why only for and against? How about something more nuanced?
A: The point of this is to provide a strong yes/no response. Finer-grained measures of agreement don't make much sense on an individual basis; aggregating many votes is more interesting. For example, consider how eBay's user rating system has been reduced to a like/dislike switch by users. The 'Ayes, Noes, abstentions' model has served well in politics and committees, when a division is called for.
I'm not satisfied with this answer. The "interesting" aggregation of simple votes which they mention will sometimes be housed within a single page. For example, thousands of people may give a particular URL a positive response at Digg, but it still just shows up as one hyperlink. The same could be said for other sites with significant user input (such as YouTube, Slashdot, or their own example: eBay).
Obviously, no page should be able to artificially inflate the importance of its own hyperlink votes (e.g. rel="I_represent_1_million_votes--honest"). But why not allow pages to determine the portion of their fixed PageRank contribution which is passed along to each of its hyperlinks? So a Digg page, for example, might choose to give 10% of its PageRank voting value to an item getting 2000 Diggs and only 2% to another item which got just 200 Diggs. Search engines could then benefit from the internal ranking systems of sites (such as digg) without having to understand their internal details. And we could all benefit from a more finely-tuned hyperlink democracy.