Hi Ned.

| I suspect the hard parts will be:
| 
| * dealing with bizarre file formats
| * dealing with garbage data
| * mapping whatever measurement units the data is in to fit on the 
| screen (projection, earth shape models, etc.)

It might be worth your while to look up Proj:
 
  http://www.remotesensing.org/proj

and Grass:

  http://grass.itc.it/

The core functionality of each of these can be accessed via the FFI.

Cheers

Mike Thomas.