From the Eberron Campaign Setting book, pg. 119-120:
Exotic Weapons
Ranged Weapons
Boomerang, Talenta; 15 gp, 1d4(1d3sm)/x2, 30 ft. range, 1 lb, Bludgeoning
Boomerang, Xen'drik; 20 gp, 1d6(1d4sm)/x2, 20 ft. range, 2 lb, Bludgeoning [or piercing (as per eratta.)]
Boomerang, Talenta: The halflings of the Talenta Plains use traditional boomerangs--simple curved, polished sticks designed to return to the thrower.
Boomerang, Xen'drik: The drow of Xen'drik use three-pronged boomerangs to hunt prey. Some adventuers and explorers learn to use the weapon while operating in the Xen'drik jungles, but few outside the drow commnities ever master the intricacies of the Xen'drik boomerang.
A boomerang of any sort returns to its thrower when it misses its target. To catch a returning boomerang, the thrower must make an attack roll (as if he were throwing the boomerang) against AC 10. Failure indicates that the boomerang lands 10 feet away from the thrower in a random direction.