Ultima Online has probably one of the best housing systems I've seen. The deeds are expensive, but if you can find enough flat land anywhere in the wilderness, you can build it. Can build anything from a little shanty to a castle depending on how much you have to spend and for the most part you can decorate it any way you wish.
People often sell their houses or land as well, since wide open flat land is hard to find nowadays. Though if unused long enough, houses eventually decay and it's content are open to the public before the house is removed. The act of taking advantage of this situation (and fighting off others who also want the stuff in the house) is called "idoc"ing. At least I think so anyways.
A lot of people use houses for storage or a place to show off equipment, since you can choose whether or not to make your house open to the public. Some people use houses as a place to keep their tamed/bought animals instead of stabling them. Some people use houses for dueling eachother (since it's private and out of town). Guilds use houses as a place to keep their guildstone (the thing a new member has to use to "sign up") and as a general hang out location. What you use the house for is pretty much completely up to you.
All of this, of course, means that you can invite people over to said house, random people can find it, etc. You're pretty much completely in control. You can even buy and set up vendors in your house, and assuming you actually have decent stuff to sell, it could even become a popular place for travelers to go.
Of course, a legit and (most importantly) free place to play Ultima Online is right here:
http://www.uogamers.com/
The servers been around for 10 years already, has roughly 1000 players on at all times and shows no sign of slowing down.
