alot of my favourite songs would probably be considered "underrated" by the mainstream considering most haven't gotten any radio play outside independent or college radio stations.
things like
snow patrol - make this go on forever, set the fire to the third bar
sage francis - makeshift patriot, inherited scars, escape artist
immortal technique - point of no return, dance with the devil, cause of death
bright eyes - let's not ***** ourselves (to love, and to be loved), don't know when but a day is gonna come
also bands like void, the dwarves, electric six, the dirtbombs and more.