RankForest has many more features, and friendlier interface. Unfortunately, you can track only one book for free. And you don’t get historical info; you have to register a book to track it. For more books, and more features you need to pay a monthly subscription, beginning at $3/month and up. Other goodies in the paid version include the option to add other online bookstore rankings, like Barnes and Noble, complex graphing options such as racing two books, alerts, and so on.
A cool tool is anything useful that is superior to comparable items. If you think this tool is inferior suggest a better one. You are welcome to insult a tool, but comments containing insults to individual people will be deleted. Corrections of fact are always welcomed, if stated politely. Recommendations of better tools are dearly wanted and may be elevated to the front page.