The Camelizer
The Camelizer is a nice browser plugin (for Safari, Firefox, Chrome) that allows you to view historical price information for just about any item on Amazon. Also, you can set your desired price so you get an email whenever the price drops to or below your desired price. It's a great way to ensure you get the best deal on what you want. You can download the browser plugin from: http://us.camelcamelcamel.com/camelizer