Other people have mentioned Fringe, Eureka and Warehouse 13, none of which I have seen: Warehouse 13 is on one of the freeview channels, but I don't think the other two are?
ETA - Caprica. Heard only bad things. Oh, and the new Stargate with Robert Carlyle - the second season has just started airing I think? I'm surprised I don't hear more about this, but I think Stargate may be a little universe all of itself.
And ETA - The Event. I watched one episode, and despite some slightly camp girl violence it didn't really grab me.