What are some UFO sighting stories you know, either your own or ones you've heard?

I’m curious about UFO sighting stories, having just heard one from a friend of mine.

She and her husband saw a small gray “cloud” in the distance that didn’t match the other clouds around it while driving through Nevada last week. The cloud seemed to be undulating and within a minute or two, the cloud disappeared, but then became like a vague, transparent oval shape. It moved from a far off distance and came towards their car. It traveled in a path parallel to the road and passed the car close to the road, going in the opposite direction, about 40–60 feet high. Only her husband and her could see it—the other occupants in the car looked straight at it but didn’t see anything.

She’s insistent that something was there. I’m intrigued. Any other sighting stories?