Idea for the web: Hover over a link, see a small preview of the linked page

Sometimes I hesitate clicking on a link because I don't know what the resulting page will look like - it's a leap of faith. So here's a potential solution: If I hover over a link for about 500ms (just like hovering over a username on Facebook), I see a small modal popup displaying a thumbnail of the resulting page. It would be trivial for Google to implement this in Chrome.

More context, happier browsing.