[Waterfall]

A horse-shoe pit is a great addition to a backyard if you host parties. Any game you can play with a beer in your hand is a good idea. I built a pit in my backyard and it was cheap and easy.

Bocce is another good backyard game. Its easy to play and you can play right on the lawn. If you get a Bocce set spend the extra money and get a nice one.

I would definitely go for a fire-pit if you have the space for one. You can buy decent pre-made ones at Home Depot or easily build one yourself.

My ideal basement setup would include:
-a bar
-poker table (preferably one of those octagon ones that have a cover so it can be used as an actual table as well)
-dartboard
-an arcade game (golden-tee would probably be popular with guests)
-pool table (bumper pool sucks)