Only 4
Mod Nation Racers PSP
Killzone Liberation
Ratchet and Clank Size Matters PSP
and Left 4 Dead 2 on PC, but i won't start it until i buy and complete the first one.

Also, it may not count but i really want to go buy Mass Effect 2 and Mortal Kombat. However, i have the current backlog and in Sept, im giving new releases first priority(ie. Resistance 3)

Here's Mine:

Witcher 2
Crysis 2
Mass Effect
Mass Effect 2
AC: Brotherhood
Yakuza 3
Starcraft 2
KH: Birth By Sleep

I"m probably forgetting a few titles.

I'm pretty set on getting Brotherhood anyway. My buddy just finished it and has been raving about it. I like how the game seems to be less sneaking around and more action and kicking ass.

Roughly how many games does that equal? :P

I just finished AC2 yesterday and bought ACB yesterday too, but I haven't started yet because for some odd reason, I get these weird desires to jump back on CoD even though I hate Black Ops. >_>;

Retailer
GTA4
Prey
Forza 3

Arcade
Limbo
Raskulls
Kingdom of Kelfling
World of Kelfing
Serious Sam HD
1942 Joint strike
TMNT 1989
Comic Jumper
ilomilo
Trials HD
Splosion Man

As you can see my backlog for retailer games isn't that bad, but I still have a good hand full of arcade games I need to beat.

it can play up to 5 a day :P

there's some stuff I bought 2-3 years ago on Steam and haven't even installed, but as it is I don't plan to play it anyway. from recent stuff (that I may have started but didn't finish): Borderlands, Black Ops SP, AC2, I-War 2, Puzzle Agent, Jolly Rover, Death to Spies 1 & 2, Recettear, Divine Divinity, Beyond Divinity, Descent 1, 2 and 3, KOTOR, SW:Empire at War, Aquaria, Freedom Force 1 and 2, Dreamfall, Super Meat Boy, Hearts of Iron 3 (you can't really finish this one, but I bought, installed and played ONCE), Disciples 2, King's Bounty: Armored Princess... and there's more. even on the PS3 I already have a rather (for me) big enough backlog: LBP, inFamous, Demon's Souls, Dead Nation, Comet Crash...

I have five games in my backlog. 

Splinter Cell Conviction,Dirt, Bioshock 2, Zuma, and Half-life (bought it on Steam a year ago, haven't even opened it).

It will get bigger if Blockbuster does another B1G1 free sale around July 4th

I've only got some PSX imports I got last year and haven't got round to playing yet:

DQVII and Arc the Lad I - III