Some items break after striking a monster:
Other items can be used to kill an unlimited number of monsters:
A regular throw moves sideways, with a slight arc. (High enough to hit the ceiling if you're in a gap only one block high) Holding up while throwing will launch the item upward at a 45 degree angle. (starting from the object's current location in your hands) Holding down does the opposite. Smaller items will bounce a bit when thrown into the floor, larger items are effectively dropped.
Pitching Gloves give the ability to throw items much further.