Hey there....
I have some experience with super bright LEDs - I modified one of the microscopes in my lab to use one as a light source because I got sick of replacing the $25 halogen lamp that normally powers it.
Luxeon (
www.luxeon.com) makes the brightest LED's on the market but they're quite expensive and must be mounted to a heatsink or they'll quickly overheat and fail in short order. The Luxeon 5W emitters are very bright and get very hot but if they're properly heatsinked they can last for thousands of hours. All of Luxeon's emitters can be purchased mounted to heatsink but that raises the price even more. If you're interested in experimenting with these I suggest purchasing them through
www.theledlight.com (no affiliation).
Also, you have to have some experience with soldering very small and fragile leads, resistors, and DC circuits. These things have specified voltages at which they must be driven or you'll burn them out. You'll need to be at one with Ohm's law because the different emitters have different voltage drops/requirements. Also, Radioshack will not have all the resisters you'll need.
There are several wavelegths available - the white emitters are quite warm (about 4000K) and would probably have to be supplimented by blue emitters.
While the idea of lighting reef tanks with LED's may someday be a viable alternative, I would stick to small PC lamps for refugiums or nano reefs.
Another idea is a small metal halide lamp - I have a light for my mountain bike which is basically a 13W HID lamp (probably MH) - it's very bright and probably in the range of 6500K. This lamp is about 2cm long and only a few mm in daimeter - quite cute.
good luck - hope I didn't dicourage you too much! - john.
