I am currently addicted to Farm Town, the Facebook app where you steadily increase and improve your virtual farm. In a little over a week's time, I'm at level 22, with an 18x18 farm, one barn, fence all around, and presently loaded with alternating crops, most recently the onions, which by careful calculation yield slightly better than the prior 3-day harvest winner, sunflowers.
My wife introduced me to the game, with no idea that I would jump into it with such reckless abandon. Funny thing is, I found out that many of my friends at the university, including several in my area (computer center) are also fanatics. We have learned to "crop swap" (a term I think I coined, meaning I'll harvest yours if you'll harvest mine... after all, that is how the farmer can get 25% additional income from the harvest, and the guest harvester also independently gets 25% of the value of the crops harvested). And thus we aid each others' addictions, comparing notes on crop yield, fence placement, types of trees, the lack of gain from farm animals, etc. And ever-increasing farm sizes means harvesting an entire farm at once can take a half hour (that doesn't count re-plowing) which has led me to stagger my crops, so that a third come in each day (replaced by a new set of 3-day harvests such as those wonderful onions). Still waiting to unlock the purchase of pumpkins, a 4-day harvest item with a pretty good sell price.
And when I have nothing more to harvest, I find myself rearranging my arbor of trees, the run of the fences, and such. And waiting for that next increase in acreage (which by my calculations I will have, like, tomorrow). And what will it be like when I reach the 24x24 size farm? Of course there are other buildings to buy, etc. And I am thinking about using part of it to design a maze using the green hedges... with all that acreage, you've gotta just have fun with some of it, and avoid the compulsion to plow every last possible square.
The social aspect is fun. I have about 16 neighbor farmers now, and it's neat to visit each farm, leave comments, etc. It's also a good exercise in planning. The rules are pretty simple, and compared to many SIM's out there, I'm sure many would find it elementary. But there it is, pulling you in like a vacuum. Alas, I am a Farm Town addict. And I am not alone!