Web site lets you track Amazon sales ranks

I've been using a cool Web site that lets you draw graphs of Amazon sales rankings of your favorite books or other products. RankForest lets you add items to a personal collection for easy reference.

Most of RankForest's features are free, but a few require a paid membership. Here's a page where you can anonymously browse some of the things members are tracking.

Sales rankings for most items are updated hourly. Here's more information about Amazon Sales Ranks.