To start off i'll list a few i think might be interesting to see:
1.Breathless Dragon: Dragon that instead of having some sort of breath power would specialize rather in the more physical attacks, i.e. claws, tail, biting, etc.
2.Raptor: Small dragons that would attack in small packs at once and could have no special power or perhaps spew a weaker flame or some other kind of power
3.Sea Dragon: Skyrim borders the northern ocean of tamriel which the nords crossed to reach atmora. The fact that dragons have been implemented in nord lore since their first recording might mean they saw some of these beasts on the trip over. Fast, no or retractable wings, serpent body, perhaps a venom of some sort
4.Sonic Dragon: Have in place of a breath some kind of roar that would paralyze/stagger you, maybe cause slight bleeding depending on level
5.Siren: Have the power to simulate human voices to draw people in, perhaps also the ability to call other dragons to its aid