I've tried just about every flash modifier out there, mostly the original commercial versions (or a very close knockoff) and DIY versions. I'm not an Omnibounce fan. You have to get the right size, and the compatibility tables always seemed to leave out the flash guns I happened to have, it's bulky for what it does, and expensive for what it is. The Chinese knock offs are less expensive, but no more effective. It's a good start, but there are a lot of new modifiers that are a lot better. SOldBear's DIY looks like much better alternative from a number of standpoints.
My personal favorite modifier is the Demb Flip-it with the now accessory diffuser (when I bought mine, the current "Photojournalist" version with the diffuser was the only way it came). All of the others, including some I purchased or made after getting the Demb, are currently sitting in a drawer
Demb Flash Products - Flip-it! the variable-angle flash reflector
The smaller sizes fold almost flat and can easily be carried in a pocket, they fit any sized flash, and the bounce card is easily adjustable for angle to give you different ratios between overhead bounce and direct bounce. With a tilt/swivel head, it gives essentially the same lighting capability in either landscape or portrait orientation with the flash in the camera's hotshoe.
BTW, I recently bought one of his Popup Flip-its, and it's easily the best pop up flash modifier I've used, and I always carry it in a pocket. It also gives you infinitely adjustable ratios between overhead bounce and direct bounce, but only in landscape mode. In portrait, you can get a directional bounce indoors if you've got a direct line to an uncluttered wall though. . . and using full direct bounce, it's good (and very convenient) for a soft fill light source.
Demb Flash Products - Demb Pop-up Flip-it! Flash Reflector
Scott