Sony have released list with the best selling PSN titles and downloadable content packs in 2011. As you can see Call of Duty: Black Ops and Tetris are top the lists respectively.
Top 10 Paid Downloads from the PlayStation Store in 2011 (including paid PS Plus offerings)::)
1. Call of Duty: Black Ops - First Strike
2. Call of Duty: Black Ops - Escalation: Content Pack 2
3. Call of Duty: Black Ops - Annihilation: Content Pack 3
4. MLB 11 - The Show Road to the Show Training Points
5. FIFA 12 - Premium Gold Pack
6. Call of Duty: Black Ops - Rezurrection: Content Pack 4
7. Angry Birds (PlayStation Mini)
8. FUT - Premium Gold Pack
9. MLB 10 - The Show Road to the Show Training Points
10. FIFA 12 - Premium Gold Jumbo
Top 10 best-selling PSN Games of 2011 (digital games only, not full PS3 games):
1. Tetris
2. Resident Evil 4
3. Infamous Festival of Blood
4. Back to the Future: The Game - Full Series
5. Dungeon Hunter: Alliance
6. Castle Crashers
7. Limbo
8. Battlefield 1943
9. Mortal Kombat Arcade Kollection
10. Magic: The Gathering - Duels of the Planeswalkers 2012
Source: Game Informer