Crazy Egg lets you find out which links are popular on your page and presents the information in easy-to-understand heat maps. It’s incredibly well designed and a fantastic idea.

At 37signals, we’ve already picked up on a few themes of usage that’ll change the design on some of our signup pages.

There’s lots to love about Crazy Egg. They don’t call their initial release Beta, they dare charge real money for their product, and they offer a very simple product that’s just really darn useful.

Oh, and it’s all done with Rails. Crazy. Egg!