I'm a fan of underexposing my shots by 1/3rd of a stop because I'm a big fan of keeping details in the clouds rather than blowing them out and losing the details. 😉 Of course, you lose something entirely different when underexposing to much, but I still like the results better when I underexpose.
Actually, I overexposed most of these shots by 1/3 or 2/3 of a stop because of the scene and lighting situation. I knew the photo would be too dark overall if I listened to the meter on my D50, so I decided not to. Still came out a bit underexposed though, which again, is something that I prefer over overexposing a shot.
Of course, in many situations where the lighting isn't tricky, I just listen to the meter.