Last.fm gives you yearly statistics, but it's also fun to Look at your own end-of-the-decade-numbers. Here are mine:

Top Artists:
1) Nine Inch Nails
2) The Magnetic Fields
3) Trent Reznor & Atticus Ross
4) David Bowie
5) ASP

Top Albums:
1) The Magnetic Fields - 69 Love Songs
2) TR&AR - The Social Network
3) HTDA - Welcome Oblivion
4) NIN - Hesitation Marks
5) TR&AR - The Girl with the Dragon Tattoo

Top Songs:
1) The Knife - Silent Shout
2) HTDA - Keep it Together
3) HTDA - Ice Age
4) HTDA - A Drowning
5) HTDA - On The Wing

Fun fact: my top NIN Song of The decade ist Find My Way. An unusual choice, I guess...