Trouble with hydros is levers--no STI, Ergos or Double-taps for hydros. If you prefer integrated levers on drop bars, there's only one choice: BB7
Shimano has a cable-actuated caliper for road levers:
http://www.bikemannetwork.com/biking/p/BR8554
I also once saw a kludge where the owner used STI levers to pull cables to operate MTB brake levers mounted on the bar top. Pretty clever.
Magura made drop levers for their hydro rim brakes. I wonder if those levers would work with disc calipers?