You can do this by your favourite artists atm the ones you can't stop listening to, or go by your iTunes Chart/Last.fm chart etc. Mine's by my iTunes chart, my top 10 songs this week are.. you can also do it (if you do it every week like +1 -4 etc, depending if they move places)
1. Kelly Rowland - Work
2. Mary J. Blige - Just Fine
3. Britney Spears - Piece Of Me
4. Kylie Minogue - Wow
5. Alphabeat - Fascination
6. Janet Jackson - Feedback
7. David Jordan - Sun Goes Down
8. Adele - Chasing Pavements
9. Sugababes - Denial
10. Amy Macdonald - Run