At the moment,
Fable 2, finished the main quest once as a good guy now I'm intent on buying everything I can in the entire world

I've also started an evil char, but haven't put much time into her yet.
Assassin's Creed! now I know what you're going to say but I only picked this game up about a month ago and in between playing fable I'm almost finished it, but I must say wtf is up with the 90% combat gameplay towards the end? it's rather frustrating, but I really want to find out the result of the 'future' story so I will persevere.
GTA IV. Another one I picked up last week from ebay for a bargain price! haven't actually started it yet, I'm waiting till I get my lovely HD monitor before I put GTA in, out of respect

oh, and I picked up Viva Pinata for 13 bucks on the weekend as well. so far, quite enjoyable but they aren't shy about giving me awards and new things. there was a point were I unlocked about 8 things at once, and each one has a little movie... that was kind of annoying.
Roller Coaster Tycoon 2! Man, just got this out again for the first time in years! I loved this game and I still do. It is from a time where games didn't have to have cartoony graphics to be published, they could just be about the whole business side, i.e. building, finaces, advertising, park layout. phenomenal game.
DJ max portable 2. I'm am never not playing this game. It is a great way to get to school on the tram.
