Yesterday I have bought the TOPCAT (Take-Off & Landing Performance Calculation Tool )
This tool closes the missing link in flightplanning and Performace planning. It can calculate also fuel requirements based on the loading and the route of the planned aircraft.
A great feature is to submit the Loading (Fuel and Cargo + Pax) via FSUIPC or aicraft.cfg file direct to the FlightSimulator. So I use this tool together with virtual dispatch on my dispatching station to get all the required info in a flight package printed out.
More information about this tool can be found on the TOPCAT website (http://www.topcatsim.com)