Huge, very huge, hundreds, to much to count. Grew my backlog from single digit to over 300 in the last few years accross several Nintendo consoles. Recently downloaded Steam and bought Civilisation III. Didn't play it yet.
I'm not proud of myself.
Bonus: I should start doing that. I usually put anything remotely interesting on my wishlist and wait for a sale. Got 95% of my games on sale.