Here's an ingenious way to put your newsreader to work comparison shopping for you. ISBN.nu is provides RSS feeds of book prices by major vendors (Amazon, Ebay, Overstock, to name a few.) When the price changes, the feed updates.
I don't know about you, but I've been eyeing the David Sedaris box set for awhile now. Once I found it on ISBN.nu, I just added a ".xml" to the end of the URL and then subscribed to the feed in my newsreader. Now I'll get notified of lower price changes, with handy links to purchase. Beautiful.
ISBN.nu [via inessential.com]