Tom Bihn's Side Effect is a neat way to get around airline carry-on travel restrictions; it's big enough to hold a few things, but small enough so it is unlikely to be counted as a carry-on bag. It's also nice that the Side Effect can be waist-mounted, so that if you're carrying other bags like a TriStar and/or an Ego, the Side Effect won't get in the way.
But what if you want a bag with more room? What if you feel a Side Effect is too small, but a Small Cafe Bag is too large and you don't want another shoulder-mounted bag to handle? What I'd like to see is a waist bag that's sized between the Side Effect and the Small Cafe bag, with elements of both in its design. It should be something that can be either waist-strap-mounted or connected to a belt or belt loops. It should have multiple zippered pockets on the outside, as well as on the inside, and o-rings for connecting organizer pouches. It should be built so that one can sit in an airline or bus seat comfortably while still wearing the bag.
This mystery waist bag should also be useful for hikes or other outdoor or public events, like some kind of super-high-quality utility apron. I'm not suggesting that Tom Bihn would want to copy the Red Oxx Sporting Clays Pouch, and there are elements of its design that would be at odds with what I'm suggesting, but there are some similarities.
Call it the Side Kick.