General
If you have a flash unit with bounce capability, you should definitely have a closer look at the ProMax System from LumiQuest.
This plastic gadget, when attached with Velcro strips to the front or your vertically facing bounce flash, may be used in a number of ways which will be obvious from the descriptons below.
The basic attachment: 80/20
The basic attachment, avaliable also separately as ProMax 80/20 acts as a reflector-diffuser, directing 20% of the light towards your subject, and letting the remaining 80% to reach the ceiling, to provide even more diffused light. (Percentages quoted after manufacturer.)
This usually works better than bouncing your external flash against the ceiling and firing the camera's built-in flash to soften eyesocket shadows and to add some catchlights's in your subject's eyes. The light from the funny-loking grid is not only more diffused than the light from your camere's built-in flash, but also moved away from the optical axis (no red eye!).
Diffusing inserts
Quite often, however, the ceiling is not close enough to provide a significant amount of bounced light; we just cannot afford the light loss.
For such occasions the system provides solid inserts which can be placed in the reflector-diffuser by means of (what else?) small Velcro dots.
Three such inserts are included with the ProMax System: matte white, silver, and gold.
This is the configuraton I use most often. By the way: instead of the ProMax system you can buy just the LumiQuest Pocket Bouncer, which does not have the 80/20 capability, providing just a white diffusing surface instead.
Soft diffuser
If the light diffused as above is stll not soft enough, you may filter it through a semi-transparent apron (more Velcro!). This may be the softest electronic flash light available this side of a studio umbrella.
Obviously, the front diffuser can be used with or without the solid inserts, although in the latter case it may provide insufficient front light.
If you are using the Pocket Bouncer, the soft diffuser can be purchased as the Frosted Diffusion Screen, a part of the ProMax Accessory Kit.
Fitting and storage
The ProMax System fits most of bounce-head flashes by means of four Velcro strips which you attach semi-permanently to the flash head. Frankly, I found the operation result more acceptable than I expected.
The whole set folds flat and comes with a 4.5x7" plastic wallet.
Recommended
The gadget is ingenious and nicely made, and at $35 (street) it may become one of the more useful accessories you'll own. I'm glad I bought it.
One thing I would still try to improve in the ProMax System is its overall thickness. Yes, it is already quite thin, but shaving another 1-2 mm of the folded thickness seems quite possible with use of more modern materials. Also, the wallet itself is too thick for my taste; I replaced it with a much thinner (yet quite firm) plastic envelope.