I spied a medium-sized Cocoon Grid-It organizer in the Flight 001 store on Hayes Street last Sunday, and bought one. This is a board, roughly letter size, with a criss-crossing web of elastic bands. there is a zippered pocket in the back (not shown).
You just find a section the size of the gizmo you want to fit and slide your item in. The elastic has non-slip rubberized dots that will keep it in place. In this case, a Hypermac battery pack for MacBook Air (with cable), Novoflex Mikrostativ mini-tripod, lens-cleaning brush, spare Leica M9 battery, pencil and small bottle of sanitizer.
The good: works as advertised, useful for people who change bags often—just grab the whole thing and transfer it.
The bad: rather heavy at slightly over 300g, quite thick at 5mm or so (the stiffener inside is probably corrugated cardboard or plastic rather than a thinner material).
Conclusion: given the bulk and weight, you would be better off with a conventional zippered multi-pouch organizer