An Israeli defense firm, Elbit, on Thursday unveiled a portable robot billed as being capable of entering most combat zones alone and engaging enemies with an onboard armory that includes a machine-pistol and grenades. As well as bomb-sniffing and bomb disposal equipment, the VIPeR can carry an Uzi machine-pistol or plant a grenade. The weapons would be aimed using an onboard video camera.
Others have gun toting robots like South Korea's Sentry Robot pictured above
The USA has Talon robots which can be armed and turned into SWORDS robots (Special Weapons Observation Reconnaissance Detection System)
Wikipedia has info on TALON