Automatic thumbnail from post?

Is there any plugin that can pick the first image from a post “body” and display it as a thumbnail in the top of the post?
I use the more tag to display just the start of a post in a blog page. Inside the posts there are several pictures. It would be elegant if the first image could be displayed as a thumbnail in the blog/ overview page – but (preferably) not in the post’s top when it is opened.
Even better would be if the thumbnail could link directly to the post – that is, open the post just like clicking the More… link.
Thanks