I just bought a few of the 1 watt Leds from superbrightleds.

You can see them on these pages of my LC site:

Here on my engine page as engine lights:

http://www.brian894x4.com/ExpeditionLCEngines.html

Here on my interior page as a rear interior light:

http://www.brian894x4.com/ExpeditionLCInterior.html

Superbrightleds is pretty good. I've placed about 4 orders with them and each one has arrived within about 2 to 3 days of ordering them in my mailbox for $5 shipping.

The 1 watt lights are pretty good and cheaper than than the lights that roundeyes sells, which are probably the same LED, difference case.

As far as brightness, I don't know how well they'd do as rock lights. For close up interior lighting they are perfect. While LEDs do show colors much better, the real advantage is being able to leave them on forever, without draining your battery.

For rocklights, the engine will be running while in use, so I think I would invest in a set of tractor lights instead. Cheaper and you can install any halogen bulb you want from 35 watts to 100 watts.

The long string of 1 watt LEDs that SBL sells looks neat and probably would be pretty bright, but I don't think it is waterproof like the 1 watt utility lights as it appears to be set up more for case and interior lighting.

Good luck.