Power:Pyrokenisis(ex: Meredith from Heroes) or Fire Manipulation(ex: Pyro from x-men), its something i really loved to have,
weakness: Freezing or Ice
other,
power:Space-Time Manipulation (teleport, time freezing and time travel), its would be awsome =D,
weakness: high risk on changing the present and future to worse or causing a time riot or something like that