If you're reading this blog, you're probably interested in Magic finance. http://blacklotusproject.com is a site recommended to me by one of my readers, routlaw. The site seems to have copied the Google Finance style. You can look up individual cards and see their daily price trends, as well as take a peek at the top selling items and the cards which have lost the most value. A quick review of the site shows that the most popular cards by volume are Maelstrom Pulse, Meddling Mage and Dauntless Escort, while the biggest "winners" ( % change in price) were Howling Mine, Lord of the Undead and Ancient Tomb. The biggest losers were a trio of Conflux rares in Maelstrom Archangel, Child of Alara and Thornling. Check out Noble Hierarch's chart below!
I'm going to have to do some more poking around and learning about the site before I start using it as a reference point, but it seems like it could be a great complement to CardShark and StarCityGames' Sales Trends. An aside - is this a new offering by SCG? I've only just noticed it today.