Geodetic Calculations library for C# developers.
Features
o Haversine Distance
o Spherical Law of Cosines
o Equirectangular Approximation
o Bearing
o Midpoint
o Intermediate Point (By fraction 0-1)
o Destination point given distance and bearing from starting point
o Intersection of two paths given start points and bearings
o Rhumb Distance
o Rhumb Bearing
o Rhumb Destination
o Rhumb Midpoint
Documentation
It's included in the downloads section below as HTML file (GeodesyLibHTML.rar).