Originally developed for personal use to aid the preparation of my flight-training, now adapted for the internet and available to everyone!
Readyfordeparture.net is a flightlogcalculator. It provides rhumbline-tracks and rhumbline-distance with high accuracy even for extreme distances. Rhumblines however might not be your first choise for extremely long legs, but if it is, the tracks and distances calculated on readyfordeparture.net are more accurate than the outcome of the handy techniques normally taught. Readyfordeparture.net can not be used to calculate routes near or over the poles.