I happen to be a huge fan of Second Life. It was one of the first truly social online games and the first to use micro-transactions, and I feel would be a good game to, if not be played by the Game Culture class, at least looked into and examined. Second Life has always been a game of creation and social activity. I had always wanted to play with it when I heard about it initially but never got to until 7 years ago, when I had a computer that could handle running the game well, but now just about any computer can get onto Second Life, even phones.
The best thing I like about Second Life is the creation ability. If the player has a dream item the player want to make in SL then you can build it. In fact I made a version of the American Brewery (http://baltimorehistorybits.blogspot.com/2011/10/john-f-weissner-sons-brewery-aka.html) in Baltimore in SL. With SL though the player can build their own clothes, their own furniture, their own buildings, their own cities. They can can make something come to life with a few clicks. Granted it does take some time to build in SL but it feels very much like a simple 3D art program. Also right now they have it so if you wanted to make a mesh item in something like Maya or Blender you can transfer it over to SL as a mesh.
Once the player build these wondrous things SLs micro-transactions will help them be able to sell it online in the Second Life Marketplace or in SL itself. I have personally built a few things and have sold a few things myself but nothing to really write home to mom about, but there are sellers on SL that actually make a living off of it. The other excellent aspect of this is that once the player sells their items they can exchange it for real cash, or use that money to purchase something they want in world themselves.
For these reasons and many others I feel Second Life would be an excellent addition to the Game Culture Class.