I took a look at two sites, Zillow.com under Real Estate, and Last.fm under Music.
Zillow provides information on residential properties (maybe commercial too, I didn't look), including size and features, and provides an estimate value of the house. I'm not too sure about the accuracy of the figure it gave me on my house. It was about $15,000 more than what I paid for it 2 years ago. That's a good number to see, of course, but only if it's accurate. I'm guessing the number they give is based on recent sales of other property in my area, which is a standard practice as I understand it. They obviously aren't taking into account the fact that my house needs some repair and updating. Anyway, it is nice to see what the property could potentially be worth given a little work.
Last.fm looks like to be similar to Pandora, in that it creates customized radio stations based on artists you like. However, Last.fm also has features that remind me of allmusic.com, such as biographical info & discographies for artists and lists of similar artists that you can look at immediately. The site also offers you the option to purchase albums, and a social feature that allows you to create a profile, leave comments on an artist's page, and create personalized playlists. I couldn't listen to the radio feature on the desk, so I don't know how good the radio station feature is, but it looks like a site worth using.