I like the idea of getting a crazy bright headlight like the SC600, but you will also need to get at least a couple of Li-ion 18650 cells and a charger to go with it. You should read the sticky posts about Li-ion battery (and charger) safety, it's important if you want to avoid a "vent with flame" exploding battery. Executive summary: you want to stick with known-good brands. Use protected cells, or use safer battery chemistry (but those give 1/2 the run time.)
You might be happier with something less ambitious, but nearly as useful, like the Zebralight H51w headlight. It runs on a single AA cell, including NiMH rechargeables. The sc80 flashlight uses a single AA or CR123, and also rechargeable NiMH, or even Li-ion versions of those cells like 14500 and 16340/RCR123. I'm waiting for a headlight version of the sc80 myself.
The Solarforce L2 series is a resonably good low-end starting point for a flashaholic. Depending on the emitter drop-in module you choose, you might need to wrap the drop-in with some aluminum foil (or copper tape, or aluminum from a soda can) to get it working reliably (intentional design issue, avoiding patent infringement.) Expect some battery rattle as well, even with 18mm cells. Reverse clickies are standard.
There are some preorder threads going on right now for dropins using the 92 CRI Nichia 219 LED. If you get one of these drop-ins, you will probably never buy another cool-white LED - they will all look like crap in comparison.
Here's one thread about it:
http://www.candlepowerforums.com/vb...chia-219-4500k-beamshots&highlight=nichia+219
My personal preference is for Malkoff MD2 or MD3 body, optional hi-low ring, and Malkoff drop-in module. (Illumination Supply is taking pre-orders for Malkoff Nichia 219 modules already, and others are doing likewise.) But I like simple, reliable, tools that are more safety gear than toy. Go to the website, look around a bit, and then call Gene on the phone - he can surely guide you to the light you really want.