Ever finish a book that you absolutely loved, only to discover that none of your friends have read it and you are left with no concept of how good of a book it actually was? A new web app, Booklert, now lets you track the popularity of a given book via its Amazon rank. Much like Alexa, you get a graph of the book’s peaks and valleys along with its current numerical standing. Booklert sends you ranking updates with an email or a tweet as often (every hour) or as little (once a week) as you like. In addition to following the ranking of a book, if you’re an aspiring author, you can also create a Booklert “badge” to post on your site that displays your book’s current Amazon rank. When site visitors click on this badge, it automatically redirects them to Amazon where they can purchase your publication. Finally, you can keep track of the hottest and coldest books of the week – every Sunday Booklert creates new lists of the highest and lowest ranked books, along with selected other statistics (which books have fallen the most in rankings over the past week, which have risen the most, etc).