This is my favorite keychain flashlight, the Arc AAA.  It comes in grey and black and the clip can be removed.  It uses one LED, one AAA battery, has a 5 hour battery life at maximum brightness, is waterproof to 50 feet, and fits on a keychain at only 2.7 inches long.  The light is turned on and off by twisting the head.  It uses a DC to DC converter to provide maximum brighness over the life of the battery and then drops into "moon" mode where it provides enough light to read by for several hours.  This is a great alternative to the other LED keychain lights because it doesn't use expensive lithium batteries.  I use rechargeable batteries with all of my LED lights.  This light can be found online for $24.  For another $5 online, you can get the Arc LE which has a brighter LED and the light output is more pure (less blue tint). 

This is my favorite handheld flashlight, the Princeton Tec Attitude.  It comes in red, blue, yellow and black.  It uses three LEDs, four AAA batteries, has 50 hour battery life, is waterproof to 500 feet, and weighs only 2.5 ounces with batteries.  The light is turned on and off by twisting the head.  It's small size and rounded rectangular body shape feels real good in the hand.  We keep one of these in the house, in our backpacks, in our cars, at the office, in my pocket, and in her purse.  I use rechargeable batteries which produce a little less light and don't last as long as alkaline batteries but they work very well for me.  This light can be found locally for about $20 and can be found online for $16. 

This is my favorite headlight, the Princeton Tec Aurora.  It comes in blue, red and black.  The light can be adjusted up and down, it uses three LEDs, three AAA batteries, has three brighness levels, two blink modes, 160 hour battery life, is waterproof (barely), and weighs only 2.8 ounces with batteries.  The light is turned on and off by a rubber push button click switch.  It's small size and light weight work very well for a single band headlight.  The different brightness levels are nice because you need a lot less light reading a book then you do hiking down a trail.  The battery life is rated at 50 hours, 110 hours, and 160 hours for the three brighness levels.  This doubles as a handy worklight.   I keep one of these in the house and one in each of our backpacks.  I use rechargeable batteries which produce a little less light and don't last as long as alkaline batteries but they work very well for me.  This light can be found locally for about $30 and can be found online for $22. 

This is a nice handheld flashlight, the CMG Infinity Ultra.  It comes in green and has a clip that can be removed.  It uses one LED, one AA battery, has a 12 hour battery life and is waterproof.  The light is turned on and off by twisting the head.  This light is very similar to the Arc AAA except that it uses the larger AA battery for longer battery life.  Do not confuse this light with the CMG Infinity (non-ultra) because that light is a joke at half the brighness.  If it isn't green it isn't the Ultra.  I use rechargeable batteries which produce a little less light and don't last as long as alkaline batteries but they work very well for me.  This light can be found locally for about $20 and can be found online for $18. 

This is a nice handheld flashlight, the Princeton Tec Impact 2.  It comes in red, blue, yellow and black.  It uses one LED, four AAA batteries, has 50 hours of battery life, is waterproof to 500 feet, and weighs only 2.5 ounces with batteries.  The light is turned on and off by twisting the head.  This light is very similar to the Attitude except that it has a focus lens that projects the light over a greater distance.  The only drawback, over the Attitude, is that it produces distictive light rings at shorter distances which can be distracting for close up work.  I prefer the attitude for hiking and general close-up work and I use the Impact-2 for distance use.  The light is turned on and off by twisting the head.  It's small size and rounded rectangular body shape feels real good in the hand.  I use rechargeable batteries which produce a little less light and don't last as long as alkaline batteries but they work very well for me.  This light can be found locally for about $20 and can be found online for $18. 

The Princeton Tec Impact is a larger version of the Impact-2.  It uses one LED with a special focus lens, four AA batteries and is waterproof.  The light is turned on and off by twisting the head.  With four AA batteries and weighing in at 5.7 ounces, this light is kind of heavy and bulky.  It's not good for close work as the focused spot is kind of distracting.  This light can be found locally for about $30 and online for $20. 

The Petzl Tikka is similar to the Princeton Tec Aurora in that it has a single strap, uses three LEDs and three AAA batteries.  The light has no up/down adjustment which is a major drawback and the LED unit is bulkier than the Aurora.  The light is turned on and off by a slide switch that doesn't feel too reliable.  This light can be found locally for about $35 and online for $30. 

This is the Black Diamond Moonlight.  The light can be adjusted up and down, it uses four LEDs and three AAA batteries.  The light is turned on and off by a rubber push button click switch.  The center headstrap and back mounted battery case makes this light bulky and less convenient.  This light can be found locally and online for $34. 

If you prefer AA batteries and don't mind the extra size and weight then the Lightwave 2000 may be your solution.  It uses four LEDs, three AA batteries and is waterproof (barely).  The light is turned on and off by twisting the head.  One problem with this light is that this light dents battery contacts pretty severly.  This is a real problem if you use rechargeable batteries and expect them to last a long time.  This light can be found online for $29. 

This is the Princeton Tec Matrix.  The light can be adjusted up and down, it uses three LEDs and two AA batteries.  The light is turned on and off by twisting the head.  This light is quite bulky and the center headstrap makes the light less convenient.  The battery compartment is almost as bad as the Illuminator and the light output level is quite low.  I would not recommend this headlight to anyone.  This light can be found locally for about $50 and online for $40. 

The Illuminator uses the same LED head as the Lightwave 2000 flahslight.  The light can be adjusted up and down, it uses four LEDs and three AA batteries.  The light is turned on and off by twisting the head.  This light is heavy and quike bulky.  The battery compartment is a joke.  Besides being quite difficult to change the batteries, it only took three changes to break the battery door.  I would not recommend this light to anyone, for any purpose.  This light can be found online for $39.