A lot of photographers are intimidated by flash when they're still trying to figure out exposure in ambient lighting conditions, but once you figure out what you're doing, it's an invaluable tool to have.
I was hiking this weekend, and I ran into a couple who wanted me to take their picture in front of a big ice formation. They were standing with their backs to the sun, and we were half in a cave to begin with, so I popped up the flash on their camera and snapped a photo. The girl thought I was nuts, so she asked me to take one more with the flash off, and I obliged. When I handed her camera back to her, she looked at both photos (the couple was nearly silhouetted in the second shot) and said, "Yeah, I guess the one with flash came out better."
;-)