TIGER/Line 1997 data set to be released as GPL
I've written for simulation purpose a GPS Simulator wich requires YUMA format almanach files to work. I've also written a trajectory simulator (WGS based) which derives a position, speed and attitude from initial conditions (Position, Speed, Acceleration and Attitude).
I though this migth interest you (in order to test you program worlwide). The program is C++ and uses a propriatary matrix library (I cannot release it under a GPL like license in its current form but I've planned to do so if it's of interest to so).