The jack stand is often overlooked and underappreciated. But if you've ever watched in horror at the glacial inevitability of a car slipping off of a jack, you know how important they can be.
Anytime you lift a vehicle, supporting it with jack stands is recommended. Anytime you plan to have any part of your body underneath a vehicle, they are a must.
Tire Rack has an Aluminum Jack Stand Set to match its Aluminum Service Jack. I use these when changing my oil and they have served me quite well. The floor jack has never given me any trouble, but when my face is under the car, I definitely want jack stands acting as back ups.