I've had numerous dreams involving U2 over the years. I think they've often held the place of a goal to be attained, or thwarted, in my dream. Usually it involves seeing them perform at some venue that they'd have no business playing in: high school stadium, in a bar (and ON the bar), etc. I think I've also had a dream where somehow I was with them onstage, just watching.
They were much more frequent in the 90's, which I think reflects when they were most "important" to me.