With respect to GTOPO30, I'll give you guys a VB utility to convert the GTOPO30 DEM files to an indexed greyscale BMP file as soon as I finish it.
Neither GIMP nor Corel can directly import the MSB ordered 16bit signed integer files (at least that I can figure out) the USG software blows up when you try to run it on every machine I've tried, FW tools contains a tool that's supposed to but gives an error message whenever you try to save out to any kind of a file (apparently needs "Python" installed, and I don't have) and 3DEM will create greyscale bitmaps if you make your own grey scale colormap (which is laborious)- but is nearly impossible to create height maps that are to horizontal scale because you have to zoom in just the right amount and then save an image of the scaled down version in the window - and there are no tools to let you select an exact sized area to view.
According to NHawk, Photoshop can read them - but I don't have PS.
I'm tired of messing about with it, when I can just write a file conversion utility and be done.
GTOPO30 will be a great source of terrain though, because at a scale of 1 KM it's not too far off from the 1/2 mile scale of AH.
(You guys can tell what I've been doing, huh?)