Recently, one of the most requested Google Webmaster Tools features I have been hearing through the forums either directly or indirectly is the ability to mark links as links you do not vouch for.
Even though we have said time and time again that links can't hurt you, no one believes it. Not only do people feel they can hurt you, they feel they can kick you while you are down already, which makes it even worse. Once Google penalizes your site for having bad links pointing to it, Google expects you to contact the people linking to you and make them remove the links. Good luck with that!
That is why Webmasters want a feature to opt out links from counting in Webmaster Tools. Yahoo Site Explorer has it, so maybe Google should follow the lead. Here is how Yahoo Site Explorer works.
(1) Login to Yahoo Site Explorer
(2) Click on your inlinks link
(3) Mouse over a link and notice the "report spam" button:
(4) Click the report spam button and you are taken to this page to confirm the request:
After that, then supposedly, Yahoo won't count that link against you.
If SEOs and webmasters are expected to be responsible for the links pointing to them, even if they can't control all of them, then Google must give them a way to fully control which links are counting for good or bad.
Forum discussion at WebmasterWorld.