If you want SUPER bright LED's you wont find them at radioshack. I bought some blue ones at fry's eelctronics and them things just about blind you when you look at them. When on the car they shined about 10-15 feet in front of it! It was litteraly like have two full sized mag-lights strapped to the front of it.

From radioshack the white ones probobly the brightest, I bought some of their blue ones and wasnt impressed, they looked purple for one thing, and were quite dim.

Alos, you can make LED's brighter by reducing the resistance of the resistor used with one, for instance 470ohm is the standard resistance used with an LED, but if you go down to say 220ohm the LED will be a bit brighter, dont go down too far though as it will eventually burn up the LED.