Not 100% sure this is the right place to post this, but I created a single-use widget for calculating resonant orbits to deploy satellites into a circular orbit at regular intervals along that orbit. It’s at http://meyerweb.com/eric/ksp/resonant-orbits/.
In case you’re wondering “what the heck is this?”, a resonant orbit is most commonly used to set up CommNet constellations around non-Kerbin bodies. Suppose you want to put three relay satellites into circular polar orbit around Minmus.