The Driller is a combo weapon in Dead Rising 2 and Dead Rising 2: Off the Record. It is a power drill rigged with a spear taped to Chuck or Frank's hand. It is relatively fragile, and can only attack in one direction at a time (which makes it a poor choice for dealing with large groups of zombies), but it does heavy damage, reliably killing even gas zombies with one hit. It is extremely effective against nearly all Psychopaths thanks to its combination of quickness and high damage.
Both pieces required to make a Driller can be found in the Royal Flush Plaza, in the maintenance room near the entrance. Power drills are next to the worktable, and the spear is just outside the red door. Furthermore, Chuck can make one with a quick foray from the Safe House: there are several power drills just outside it, and a spear in the Chieftain's Hut.
The Driller is perhaps the closest thing in the game to a definitive anti-psychopath tool, together with the Defiler and the Knife Gloves. The only psychopath fights where its use is limited are the final confrontations in "The Facts" and "Overtime". In the former, using any melee weapon is close to impossible, and in the latter, no combo weapons can be used.
The Driller's heavy attack is reminiscent of an assassination using the "hidden blade" in the Assassin's Creed series.
If Chuck is far away from the Safe House, but needs a Driller, they are found for sale at Tinkerbox, for $15,000 (less with Bargaining magazines). As pawnshop-built combo weapons go, this is relatively reasonable.