Pump_block
Original concept by fixittt, shamelessly stolen..er..borrowed by me
The idea is to have the ouput of the pump as close to the water block as possible so you can take advantage of the extremely turbulent water flow the pump impeller creates.
What could be better than having the impeller "inside" the block it's self? where the ouput from the impeller can be directed over the core area while the water is at it's most turbulent.
I have bought a small 700L/H(186gph) power head that should fit the bill nicely, it leaves just enough room on a P4 water block base to allow for 1/2'' hose barbs.