It seems that Technorati now include a "endorsement" and "vote" feature! Even though it is still experimental, it's really interesting. It is close to the idea I had with roberto one year ago. It's cool to see that paths converge!The discussion in the faq adresses problem we also had:

Why only for and against? How about something more nuanced?
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.
There are much richer ways to express this idea and similar ones using RDF and semantic web ideas
Indeed there are, but typing them by hand and remembering them is beyond most mere mortals, and automated tools don't do this either. This is meant to be very simple, memorable and easy to type in the current generation of blogging tools, that largely need manual entry of URLs. Similarly, it is easily added to an automated tool.

The syntax is pretty simple:

hree new values for the rel attribute of the "a" (link) tag in HTML. The new values are "vote-for""vote-abstain" or "vote-against", which are mutually exclusive, and represent agreement, abstention or indifference, and disagreement respectively. A link without an explicit vote 'rel' value is deemed to have value "vote-for" or "vote-abstain", depending on the application.

I don't understand why I would put a link on my blogroll that I don't like. Why voting against a blog that I link, if I don't like it, I do not link it...