Reliability, cost, watertightness, weight, runtime, lumens, size (among others) are things you'll want to know before making a purchase. Once you know these things, finding a light should be easier.
Me, I like to look at the cheaper stuff, see if any of those fulfill my needs, and if not I'll see what's available for a little more money.
Dealextreme is a good place to start. I recommend going for a Cree LED model, but it's up to you. They usually have beam shots with lots of customer input, photos and videos. Tons of nice lights, but there is a lot of junk there too. Overall very inexpensive with free shipping. Be prepared for possibly a couple weeks of waiting. Read the reviews. Go with lights with higher ratings. Do your homework, and you should be able to find a decent light on here.
http://www.dealextreme.com/c/aa-cree-flashlights-942?page=1&pagesize=52&pagesort=relevence