Needed: Taillight Recommendations

I'm looking for a good taillight -- the kind you turn on on a slightly overcast day and drivers 0.5 miles away go "Whoa, there's somebody there." Any recommendations?

The story behind my request, for those interested:
Right now I have a really wussy little two-LED one with one of those microscopic batteries that you have to go to a specialty store to replace. Irritating! My DH bought it to replace the Blackburn Mars 3.0 rear light I had (which got jolted off my bag on some commute and was, alas, never seen again); he said "I thought you'd want me to get a nice cheap one." Um...

My commute is all in daylight right now, but the other day we had this horrific dense fog that scared the living daylights out of me to ride through, since I *knew* cars behind me couldn't see my little light (I also wear a Whisper neon-yellow vest, but in the fog, it wouldn't do much good). Then yesterday I rode in through a thunderstorm in the kind of torrential rain that reduces visibility to about 6" in front of you. Again I wished for a good, bright blinky rear light. And of course in the winter I need something attention-getting.

I just got one of these:
http://ecom1.planetbike.com/planetbike/media/3034.jpg

On flash mode, it's so bright I won't use it when I'm riding with other people. I just wish it had better mounting hardware. Right now it's clipped to my seat pack and hasn't fallen out yet - I'll have to jerry-rig something to get it onto one of my oval seat stays (there is mounting hardware for a round seat stay).


ETA: I also just got one of these http://www.amphipod.com/440-448/440.gif- haven't worn it on the bike yet, only for running (hardly notice it's there unless I want to take a jacket off) - but I really bought it more for riding than running because of all the reflective material.

I love my Blackburn Mars, and I'm planning to get one of the Planetbike Superflash critters, too. Played with one at the LBS. Boy Howdy, that thing is bright! I bet it would light up the fog around you beautifully.

The Superflash is a great light. The other recommendation that I'll add is the Cateye TL-1000/1100 (earlier/later models). 10 LEDs, with 6 facing back and 2 on each side. On the more random flash patterns, it's completely obnoxious. It uses AA batteries too :D

I've got the Blackburn Mars 3.0 on all three of my bikes. You can secure it a little better using using a tie wrap if you are mounting it on your seat pack. The seat post mount is very secure and won't bounce off.

Another vote for the Superflash. When I was trying them out in the store I could look at all of the other tail lights, but that one left me blinking and seeing spots.

I'm another that can highly recommend the superflash. There is no problem being seen with one of those. Living in Portland, we have 9 months of rain and fog. Works great. (If I remember correctly, Susan O. has 'em on her bike too, if ours isn't enough of an endorsement. ;):D)

Knog Bullfrog? that's a pretty cool and bright one.