Princeton Tec Attitude.
http://www.princetontec.com/index.php?q=attitude The Impact II is practically the same light.
Not a super bright light, but most things you need a flashlight for you don't need a super bright one. I use this light for everything except shining the tops of tall trees when coon hunting. I use a mining type coon hunting light for that.
The Attitude is small enough to carry in your pocket, uses 4 AAA batteries, and has 150 hour burn time, so your batteries are never dead. You change them about once every year. It is rugged, it twists on/off - no button switch to fail. It is just one of my most dependable pieces of gear, and I always have one in my pocket. Price? Less than $20.
I have two or three of them. Never had one fail, and have never had dead batteries. I change them once a year. Right before hunting season. They are more than bright enough for blood trailing, in fact I have used my coon light for blood trailing before, but I prefer a light than it not so bright just in case you bump the deer. My coon light on bright will spook everything in the woods including nests of yellowjackets.