that video
guy has sucky looking shields. I can picture waaaay cooler stuff.
First off, the 4th edition "Gauntlet Axe" from Dark Sun. Imagine your shields as being sort of like battle axes, protruding from your bracers/armguards. As a double-half-moon design, it would look a lot like a round-ish shield on each forearm, even to the extent of having a spike at the tip where the central shaft ends (pointing forward, from your wrists). It would look cool, AND be very axe-like. Since there is virtually no distinction between bludgeoning and slashing damage in pathfinder (AFAIK), why the heck not, just call your shields battle axes in each "hand" and call it a day. Even better, since you can't drop them (although if you let your hand go on your heavy shield to grab onto a rope, say, if you're about to fall off a cliff, not sure how that'd work).
No-penalty TWF, pretty cool idea actually.
I'd be very interested in way that one could combine the mundate "throwing shield" property, with a magical "returning" for when you need that ranged attack. (surprise! whack). Screams Capn America a little loudly, though.