I posted this as an answer to a question below but I though it could
be of general interest (and easier to search).
I haven't seen a commercial honeycomb attachment for a hotshoe
flash. That's why I did one myself.
The recipe is quite easy: just get a box of black straws, cut enough
in small pieces (2-5 cm depending on the wide/narrow beam you want)
and glue them together. Make a cardboard mold arround the flash,
fix it (glue/tape) and then remove the flash before starting gluing
the straw pieces.
I finished mine off with a 5cm thick elastic band around that's only
half glued to the cardboard, sothat the other half works as flexible
attachment to the flash.
Ingenious - but not too sure what it would be used for when used on camera. It could however be very useful when used off the camera, for example for backlighting.
Garry,
I agree with you. On camera it has no function. But when the flash is used off camera, you can use the honeycomb to create some spot effect or -as you mention- as directional backlight to avoid flare (like I tried to show in the example above)
Just one tool more give the desired shape and quality to the light.