In your MailChimp campaign stats, you can now see exactly where people are clicking in your email campaigns. Just hit the "View Email Clickmap" link in your stats page, and you’ll see your email campaign with an overlay that shows you where the clicks were.
Here’s an example from super-awesome MailChimp user The Secret Chocolatier:
It’s a great way to see where people click. Mostly near the top? Do they like pictures of products, or text links? Do different types of pictures get more clicks?
By the way, you should totally try The Secret Chocolatier’s Brownie Bites. Oh. Maggod.