Some examples of small engines:
Northrop Grumman Bipropellant thrusters:
-TR-308 Liquid Apogee Engine, which placed the NASA Chandra X-ray Observatory spacecraft into its final orbit. The Liquid Apogee Engine (LAE) is the world's highest performing apogee engine.
-TR-312 Liquid Apogee Engines (TR-312-100MN and TR-312-100YN) which have completed DVT testing for commerical geostationary comsat applications.
-TR-500 Secondary Combustion Augmented Thruster (SCAT) Bi-Modal Thruster, flight-proven on the National Reconnaissance Office's Geosynchronous Lightweight Technology Experiment (GeoLITE) program.
-TR-711 Gel Boost Engine, which powered the world's first flight of a tactical missile utilizing gelled propellants and achieved a 700:1 Thurst-to-Weight Ratio.
-LOX/LH2 and LOX/Ethanol RCS engines successfully test fired in 1000 lbf and 870 lbf configurations, respectively.
-NASA RCE contract for a 100 lbf class LOX/Methane.
Monopropellant thrusters - several models between 1 and 86 N, using hydrazine.
Monopropellant thrusters, hydrazine, 1-3100 N.
Biprop thrusters, MMH/NTO or Hydrazine (N$_2$H$_4$)/NTO, 22 N-4 kN.
bipropellant thrusters 4-200 N, MMH and N$_2$O$_4$ or mixed oxides of nitrogen (MON)
hydrazine thrusters 1-400 N
Apogee engines, MMH and N$_2$O$_4$ or mixed oxides of nitrogen (MON)
ion engines, thrust 50 $\mu$N to 200 mN