I frequent hypem.com
People blog about music and this website aggregates these into music listings that one can stream.
Click on the play button beside the heart on each track to listen.
Anyways, I was just on the site and I found the Time Machine feature which has the top 50 songs from the last 5 years.
So this is like a cheat-sheet of hip music. Get at it!
http://hypem.com/popular/week:Oct-22-2007/3
enjoy,
– J