rlange - 1:01 pm on Jul 8, 2011 (gmt 0)
A -1 button for people who don't like your site?
They already have something like that. Do a search, click on a result, then hit the Back button within a few seconds. You'll notice that there's now a "Block all www.example.com results" link next to the "Cached" link.
That's per-site, though, and the +1 is per-page, so it's probably more like a "-5 button".