See also:
Expr::minDistance()
See also:
http://docs.mongodb.org/manual/reference/command/geoNear/
See also:
http://docs.mongodb.org/manual/reference/operator/minDistance/
See also:
http://docs.mongodb.org/manual/reference/operator/near/
See also:
http://docs.mongodb.org/manual/reference/operator/nearSphere/