The most useful robots onboard currently are the SSRMS and JEMRMS, both are teleoperated robotic systems.
The JEMRMS (Japanese Experiment Module Remote Manipulator system) is
a 10m long robotic arm, mounted at the port cone of the PM, intended to service the EF and to move equipment from and to the ELM. The RMS control console was launched while inside the ELM-PS. The main arm was launched with the PM. The "Small Fine Arm", is 2m long and attaches to the end effector of the main arm, was launched aboard.
(from Wikipedia) Acronyms: PM - Pressurized Module, EF - Exposed Facility, ELM - External Logistics Module
The SSRMS (Space Station Remote Manipulator System)
Launched on STS-100 in April 2001, this second generation Canadarm is a larger, more advanced version of the space shuttle's original Canadarm. Canadarm2 is 17.6 m (58 ft) when fully extended and has seven motorized joints. It has a mass of 1,800 kg (4,000 lb) and a diameter of 35 cm (14 in). The arm is capable of handling large payloads of up to 116,000 kg (256,000 lb) and was able to assist with docking the space shuttle. Officially known as the Space Station Remote Manipulator System (SSRMS), it is self-relocatable and can move end-over-end to reach many parts of the Space Station in an inchworm-like movement. In this movement, it is limited only by the number of Power Data Grapple Fixtures (PDGFs) on the station. PDGFs located around the station provide power, data and video to the arm through its Latching End Effectors (LEEs). The arm can also travel the entire length of the space station truss using the Mobile Base System.
Most of the time the arm operators see what they are doing by looking at the three Robotic Work Station (RWS) LCD screens. The MSS has two RWS units: one located in the Destiny module (US Lab module) and the other in the Cupola. Only one RWS controls the MSS at a time. The RWS has two sets of control joysticks: one Rotational Hand Controller (RHC) and one Translational Hand Controller (THC). In additional to this is the Display and Control Panel (DCP) and the Portable Computer System (PCS) laptop.
From Wikipedia
Note that no one involved with the SSRMS ever refers to it as the Canadarm.