Rush. Of the times I've seen them, probably the Moving Pictures tour. Xanadu would have to be my fav.
AC/DC. Seeing them in Nuremberg was the more memorable show, but I got to go backstage and hang out for awhile after a local show. Seemed like great guys, very friendly, we were treated very well. Hard to pick a particular song, Angus makes them all pretty memorable. Hell's Bells live, with the Bell hanging in the middle of the stage was pretty cool.
Ricky Nelson. No, really! I was in Florida visiting my uncle during a break around December 25 or so. We went into Orlando and there was a lot of pre-bowl game things going on, Ricky Nelson was playing on one stage. His music is not really my main like, but I was just blown away at how tight this band was and how great they sounded. I believe it was his next to last show.