Wow! Thanks for all the encouraging comments and kind words everyone... very much appreciated!
A few of you folks have guessed correctly - these are all using a custom designed snoot that I put together. It looks like crap, but works pretty well. The snoots fit over my DS125s and can produce beams of light anywhere from 12-inch diameter all the way down to about 2-3mm diameter.
As for this becoming a product - maybe some time in the future, but these things I'm lugging around are sort of heavy, ugly, and just so stupid looking that they'd probably scare more people away than they'd attract. Not dismissing the possibility of redesigning it though, just not sure if the demand is there to warrant production.
davichin - you're right, they can be difficult to aim, but when you nail a shot with them, it can really turn out well! Each of the shots posted took between 30-120 minutes to shoot.
Here are a couple more snooty shots showing the tip of the lighting rig:
Horseshoe crab eye
Nikon D300, 105mm lens, +10 diopter SubSee
1/250, f20, ISO200
Horseshoe crab eye with snoot
Nikon D300, 105mm lens
1/60, f14, ISO200
The same tube worm from above, with snoots showing (those are 8mm thick pen bodies)
Nikon D300, 105mm lens
1/320, f22, ISO200
And here are a couple more that I think turned out well:
Stargazer
Nikon D300, 105mm lens
1/250, f22, ISO200
Baby skeleton shrimp riding on mother
Nikon D300, 105mm lens, +10 diopter SubSee
1/200, f20, ISO200
Tiny nudibranch
Nikon D300, 105mm lens, +10 diopter SubSee
1/200, f20, ISO200
Urchin
Nikon D300, 105mm lens
1/200, f16, ISO200
Octopus
Nikon D300, 105mm lens
1/320, f20, ISO200
Keri
