Animal Crossing: Wild World
I've been playing ACWW on a daily basis for a while now. At first I spent some time fishing and bug-catching for the museum (I hate my neighbors), but lately I just put in half an hour a day to check for fossils and collect some cash. My long-term strategy is just to make a killing in the Turnip market and get my mansion.
There is a lot to do in ACWW, way more than in the Gamecube version. But the true genius of the game is that it's very approachable for casual play. If all I want to do is harvest fruit trees, I can do that. If I just want to extort my animal neighbors, that's possible too. Wi-fi town visitation isn't especially useful - mainly just for trading goods from person to person - but it's pretty easy to do.
Wild World is what you make of it, and though it isn't very engrossing (unless you really want that Golden Watering Can), it is easy to pick up and have fun.
Progress: Three floors!