We now know that virtually all galaxies contain a population of globular clusters (GCs) with remarkably similar properties (age, luminosity, metallicity...). Because GCs are luminous and often found at large galactocentric distances it is enticing to try and use their kinematic properties to determine galactic mass and mass distribution. To date there are more than two dozen GC systems with 100 or more known cluster velocities. I will briefly present the data and some of the simple results, leading to discussion of how well they can do this job