One that raises like 900 million skeletons from the ground to fight for you for a limited amount of time would be nice..
Maybe not something exactly like this but I'd love something similar. Would be awesome to have a few shouts that would match the style of character or the "class" you're trying to play. Like for a necromancer type character you could have a shout that summons a couple skeletons at the lowest level of it, maybe 4 at the second level, and perhaps up to 6-8 at the highest power of the shout. And powerful fire, ice and lightning shouts would be great also. Just a few that are over powered versions of current spells or something like that (maybe make them a little more special or unique than just over powered current spells, could be a little more spectacular) to go along with the unique ones that are already confirmed, like the slow time one.