Here in the US of A, we apparently have no standards at the state or federal levels regarding bike light beam shape. Consequently, the only common choices available from any retailer (from Wal-Mart to specialty bike shops) are basically insanely powerful flashlights (we are, if nothing else, a bigger-is-better society) which attach to various parts of your bike or body. They are powerful enough, that I use a cheapo light which was retired from bike duty a couple years ago as a flashlight in my workshop. I suppose symmetric beam patterns are fine if you ride off-road, but they are not great when you ride on the road. One, such lights waste a lot of the light they generate. Light goes up and to the sides just as effectively as it goes down and to the front. Two, a good chunk of the light which doesn't illuminate your path serves mostly to blind oncoming bikes, cars and pedestrians. Even off-road, I have to question the utility of over-illuminating everything other than your path.
Over in Germany they do have a bike equipment standard, StVZO. I don't know what all the details are (it applies to other bike factors besides lighting), but it at least legislates headlight beam pattern. This is a good thing. More of the light generated goes where you need it -- on the road -- and much less of it goes where you don't. Consequently, the lights themselves don't need to generate as much raw output. You can get by with a lower power light which will last longer between charges or battery replacement.
I use a Philips SafeRide on my commuter, but there's nothing special about it. (I like it, but my intent here isn't to promote a specific light.) There are plenty of options available. In fact, if you search eBay for "StVZO" you will see lots of battery powered lights which advertise StVZO compliance. They don't seem to be any more expensive than their super powered flashlight brethren. Many are produced in Asia (no great surprise there), which probably helps keep costs down.
If you're looking for a new bike light, I think you should consider one with an StVZO-compliant beam. If you prefer to shop locally, ask your LBS what they can get their hands on. If their only option is to sell you what they can get from their distributors, ask them to lean on those folks. If that doesn't produce results, vote with your wallet and find something online.
