[http://feeds.feedburner.com/~r/TheLongTail/~3/141612509/the-coolest-new.html The coolest new feature on BookTour: Auto-favorites]:
Like any other startup, we’ve adding new feature nearly every day on [http://booktour.com BookTour]. But my favorite is one that we added last week. You know the music services, such as [http://www.sonicliving.com Sonic Living], that’can scan your iTunes or LastFM’libraries and then automatically tell you (via emails or RSS feeds) when’your favorite’bands are coming to your town? We wanted to do the same for books and authors.
So now if you go to your Profile page on BookTour.com, you can enter your Amazon login info and we’ll automatically look up all the books you’ve ever bought and add those authors to the list you’re tracking. If any of them are coming to your area to give talks or other appearances, we’ll send you an email or include it in your RSS feed. And you can always use the service to ping those authors and ask them to come speak to your company, organization or just book club while they’re in town.
[http://www.longtail.com/the_long_tail/WindowsLiveWriter/bt.png 
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How cool is that?!
(BTW, we don’t keep your Amazon info. The site just opens a secure connection to Amazon, fetches the books from your order history, and then closes the connection and discards the login info. That means you have to enter’the login’again when you want to refresh your favorites list in a few months, but it also ensures that your login information can never be compromised.)
(Via [http://www.longtail.com/the_long_tail/ The Long Tail].