Hi there,
Usually when you use high power LEDs you also use some other devices
like 'optics' to direct the beam so it projects a beam instead of just
a wide area light. The Luxeon Star for example has two different
optic director lenses that can be used to make a pretty good flashlight.
There are many other types of LEDs out there these days however.
BTW, for a flashlight, you probably want a 'white' LED, not a colored
one, where the wavelength might come into play. White is made of
many different wavelengths of light but the LEDs are simply called
"White".