I'm using a single flood style LED bulb at a 45 degree angle, aimed from the front left corner of the tank to the rear right corner. This way I get directional light, shadows, and shimmer.
I mounted a clamp light base inside my canopy by removing the clamp and then using a washer and screwing it into the wood canopy. The metal is thin enough to bend it to fit into the corner and anchor it there with the screws. I put the washer there because the metal is thin enough I didn't want it to tear or stress enough to slip off the screw. Clamp light -
http://www.lowes.com/pd_203213-1373-FL-300NPDQ12_0__
I ran the wiring on the inside of the canopy and anchored it so it had a drip loop.
The bulb I used is a Sylvania 8 watt, 500 lumen, 5000k bulb, 40 degrees. On the bulb it says - LED8PAR20/DIM/850/FL40/G3, suitable for damp locations. I bought it at Lowe's a few years back, the closest thing I see online tonight to it is this bulb.
http://www.lowes.com/pd_592644-3-79074_1z10hrhZ1z10ht4Z1z140ll__?productId=50223599&pl=1
This lighting system is mounted on my 150 gallon tall which is 48" long, 24" wide, and 31" tall. It's plenty of light for this tank but if this was a shorter tank you may have to either play with the angle or the lumen output, this would overpower a shorter tank.