I really enjoyed Fallout, a game that you would pick to go to a desert island with.
Other games that are must haves:
Modern Warfare 2
The Drake's Fortune Uncharted series
Batman
I have my system hooked up to a mammoth home theater but having a baby in the house forces me to use headphones on occasion. Here is what I wear:
http://www.sennheiser.ca/live/senn/produit/en/105/14
I bought these at Axe Music (great store) but I had a $100 gift card which made them worth it. They have such crystal clear sound...even through my home theater I miss sounds so I prefer the headphones.
The PS3 is hooked up to a 48" Bravia 1080P Television, my 360 is hooked up to a 36" HD CRT (seems ghetto yet has the clearest picture possible). I may retire the CRT for the 48" and go with projection or a 55" LCD in the theater room.
I am hooked up through my wireless network, but play most on line games through my 360 which is wired in my basement (through a gigabit router). The PS3 is in our home theater which is where we spend most of our tv time, so I wanted the 360 to be somewhere in the house where I could yell through my mic without waking the house up. I buy the 360 versions of games when I want the game for on-line play, PS3 for local play. On occasion, I will use the PS3 multiplayer, but find the 360 vastly superior in every way for on-line gaming.
I do not use the PS3 for any other purpose besides games and movies. I know some people hook it up to play videos from their PCs, I don't.
I also use gamefaqs.com for any video game related questions, been a user of that site since nearly day 1.