This is a very nice LGPL SDK for projecting geospatial objects to a 2-D space. Written for .net.  A geospatial library handles the translation of geo based vector data into it?s 2-Dimensional representation.  This allows you to render your own maps from vector data in different projections.  What this library does is very similar to what happens when a 3-Model is rendered unto the 2-D screen by a 3-D rendering engine, only this is for map data.

Sharp Map  

Free Geo Spatial data is available from www.openstreetmap.org.  Now you have everything you need to build your own Google maps, or virtual earth replacement.  (Well, that and about about 100,000 hours of developer time :)

This is how you calculate the distance between two points on on the earth.

Haversine formula:  (^  = Change in)

R = earth?s radius (mean radius = 6,371km)
^lat = lat₂- lat₁
^long = long₂- long₁
a = sin^2(^lat/2) + cos(lat₁).cos(lat₂).sin^2(^long/2)
c = 2.atan2(Sqrt(a), Sqrt((1-a)))
d = R.c

(Note that angles need to be in radians to pass to trig functions).

JavaScript:

var R = 6371; // km
var dLat = (lat2-lat1).toRad();
var dLon = (lon2-lon1).toRad();
var a = Math.sin(dLat/2) * Math.sin(dLat/2) +
        Math.cos(lat1.toRad()) * Math.cos(lat2.toRad()) *
        Math.sin(dLon/2) * Math.sin(dLon/2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c;

More info (including bearing)

http://edn.esri.com/index.cfm?fa=media.detail&media=145

Free (and pay) online services for creating/generating maps, geocoding and visualization of maps.