and Hype Machine. some one posted it already. but it wasnt on the blog, and it is fucking amazing. it takes every song that is ever blogged and puts it in one place and then everyone votes on them. then it makes the "popular" list which is the top rated songs blogged in the last three days. basically you get all of the best songs in the world as they come out. unfortunately lil wayne and drake tend to infiltrate the list but just ignore them. Also the radest mashups always make it on there, like hathbanger, hood internet and the like. and you can use it to search for songs, then download them.
Really not sure how "Unknown" it is but this is like Pandora mixed with Playlist.com. Grooveshark lets you search for music you want to hear, make a quicklist/playlist, and lets you like songs so you can view them later. You don't have to register to listen to Music so it is nice when you just want to look up a song or just make a quick playlist to listen too.
Mac Buying GuideWell only really comes in handy when you're buying an apple product, but it lets you know when to buy each product and an estimated time that the product is going to come out. This helped me buy 2 computers and 3 ipods... and i could have been stuck with the last generation. Gotta love this sitehttp://buyersguide.macrumors.com/
www.skimoviemusic.com has probably been put up already but if not it has all the tracks from pretty much very ski movie every year since Blizzard of Aaahs so if your looking for that tune from someones killer edit it lists them pretty easily and sometimes gives an iTunes link.