Since I got kicked out in the first round, here's my entry to Paizo's RPG Superstar contest. Last year I went with the Bear of Holding, so I figured I'd try something more conventional. Turns out I still can't grok what they are looking for.
Claws of the Bulette
Aura moderate transmutation; CL 11th
Slot hands; Price 52,800 gp; Weight 1 lbs.
Greatly valued by duergar and other races of the deep, these red iron gauntlets end in cruel claws curving over the wearer's fingertips. For eleven minutes per day, divided up as the user pleases, the gauntlets allow him to cleave through sand, loose earth, and packed soil (but not solid stone or metal) just as a landshark would with a burrow speed of 20 ft. A favored tactic of duergar skirmishers raiding dwarven citadels is to burst forth from the walls with a mighty leap, brandishing their Claws of the Bulette, as once per day when emerging from the surface of the earth while using the burrowing power of the Claws the wearer can execute a particularly lethal barrage of attacks. Upon making exiting a surface and making a successful jump check (DC 20), the wearer of the Claws can unleash a full attack while still having moved up to their normal burrow speed through the earth, just like the leap of the landshark.
Requirements Craft Wondrous Item, beast shape IV; Cost 26,400 gp