This mod adds a part to KSP that provides a window for planning trips between any two bodies in the system, including between two moons, or from a moon to a different planet.
Protractor v2.4.5 (updated 2/11/14) – compatible with KSP v. 0.23 (and added to tech tree for campaign mode!)
See the forum link below for video walkthroughs and more information.
I do not regularly check these comments. The best way to reach me is in the KSP forum thread for the mod: