Hmm, underated... I'd definitly say Purgatory is their most underrated single, by far! Fear is the key on the other hand I feel is underrated in a totally different way, it's not a top maiden song, but for me it certainly is a top third on the album. But almost noone ever comments on it, and if they do, it's in negative words, wich makes me think it falls into the underrated category. As a third and final I think the flight of Icarus is underrated, much in the same vein as purgatory, some people like it and it was a single, but a lot of hardcore Maiden fans don't give it much love, which I feel is a bit sad. especially the way Nico slightly touches the tom in an almost march-drum-esque fashion is brilliant. Anyway, that's my two cents. =)