Let me add to Mike's list in that if you live in a cold climate, you'll want to add -- if possible -- a (ball) valve inside your home so that you can easily drain the water from the outdoor faucet at the beginning of the winter.
Outdoor faucets have a valve stem that goes well inside the house in order to keep the faucet warm so that the pipe does not freeze. In cold climates, this may not be long enough.
Adding a ball valve should cost you less than an additional $30. If you are doing the work yourself, the valve itself should cost less than $10. You'll be glad you did. A burst frozen pipe will cost you a lot more than $30.
Also, make sure that the water line goes -through- an outside wall and never along or in an outside wall. Even insulated walls are not warm enough to keep an outside pipe from freezing. All you need is one pinhole leak and it's curtains. I've been there.
Check with local building codes and building department to make sure that you are even allowed to add an outdoor water line. I know that I can't add an extra outdoor faucet (I have 2) in my house because Boulder's code says that I am at my maximum fixture count. An outdoor hose bib counts as 3 units here. As a comparison, a sink is one unit. If I want to add a single water fixture to my house (and be legal) I would have to increase the meter size at a cost of about $20,000. You read that correctly.