I really missed out on Phantasy star online. It's lame by todays standards but for the time it was probably pretty epic.
Also, I'd love to try little big planet but I doubt it's gonna happen. That game looks like an instant classic and it's a shame to miss it.
Btw, GTA4 online was horrible in my experience. It was fun to mess around in but I never saw anyone taking it seriously and doing stuff. Every time I logged in people were just clustering and killing each other. I didn't bother with any race modes though. Who plays GTA to race anyways?
In closing, I'm sure many people were pissed with Halo getting number 1. Halo is kinda similar to FF7 in the way that about half the people loved it and the other side thinks it's overrated garbage.
Personally I agree with it being number 1, for online. The offline/campaign content never really interested me. Other FPS games did that much better but that's for another list.
@ChrisP- The best part of GOW(2) online was the horde mode. Maybe it's just me but I think the concept of 4 player coop vs waves of enemies is awesome. It's awesome in Halo Reach too but they don't let you go for 50 rounds, just 1 that lasts about 10 mins

GOW Horde mode ftw.