I don't have a good definition of "infrequently-performed", it's in the eye of the beholder I guess. I've seen a few minor oddities, but nothing truly earth-shattering. The closest I've come to *really rare* was at my first U2 show in 1987, when Bono sang a few lines of "Walk to the Water" during "40". I've also seen, in no particular order:
- Do You Feel Loved?
- Crumbs From Your Table
- Your Blue Room
- Fast Cars
- Eddie Vedder & Daniel Lanois guesting on One / Old Man River
- One of only two 2005 performances of Discotheque, complete with Popmart intro
I'd be curious to know what the rest of you have been lucky enough to witness!