I recently bought a Planet Bike SuperFlash tail light. What I really want is this one (here's a better picture of it's power), but owing to my lack of money, I started digging through Nashbar in the hopes of finding a cheapblinky red-LED light. James recommended the SuperFlash, as it actually uses a 1/2 watt red LED. The more power the better, I say, and because it was on sale for almost half-off, I jumped on it.
Though I haven't actually gone on a night ride with it, I did use it as a flash light around my house last night and this morning. (I always look for ways to play with my new toys--even if I can't use them for what they are made for.) This light is bright. In fact, it seems--though I don't have the tools to test it--much brighter than my 1 watt front light. Pictured here is a shot taken with the light on in my bike's bedrooom--yes, my bike gets its own bedroom (though it has to stay in the garage when people come to visit)--which shows how bright it is because my little cheapo camera metered off the SuperFlash.
There are two modes: obnoxious blink and steady. For the blink mode, there are two additional standard (low-powered) red LEDs in addition to the 1/2 watt. They alternate: little blink, BIG BLINK. This is what makes them obnoxious. It fools you into thinking it is a plain-old blinky and then WHOA, that's bright. Planet Bike lists burn time on blink mode as 100 hrs. (The SuperFlash runs on two AAA batteries.) The steady mode only uses the 1/2 watt LED of course--I'm not sure you'd even be able to tell if the two little LEDs were lit.
The other light here is the Knog Toad. This uses Knog's silicone wrap-around-the-bar mounting and has 5 LEDs mounted in a vertical fashion. The main reason why I like this light is the mounting. I have one of those fancy flat-top carbon drop bars on my bike which, though comfortable and sexy, doesn't work with any mounting system out there--well, except Knog's. There are three modes: steady, fast-blink, and slow-blink.
One problem I have with the way the Toad mount works (as opposed to the bullfrog, which I had for a very brief stint) is that the button is under the silicone wrap. There is, in fact, a special "button" built into the wrap part to line up with the real button in the base. Unfortunately, when the wrap is stretched almost to its limit (as it is with my bars), the buttons don't line up so well.
Again, I haven't been on the road with this one yet, so I can't comment on real-world testing. The Toad retails for $32.
These lights came just in time, too. Tomorrow starts the hunting season which means that, for the first time this year, it is safer to be on the roads than in the mountains.