Sunflash,
I took a look at Terragen. I can't make heads nor tails of that interface to be honest with you.
Here's the keys to Skycubes:
1. Camera FOV needs to be at 90 degrees
2. 6 images at the following camera positions
0 | 0 | 0 (F)
0 | 90 | 0 (L)
0 | -90 | 0 (R)
0 | 180 | 0 (B)
90 | 0 | 0 (D)
-90 | 0 | 0 (U)
Axis Chart = X | Y | Z
Set your render size to 512x512.
Once your six images are rendered (uncompressed of course), the (U) image needs to be rotated 180 degrees clockwise using any image editing software.
Then, convert all six images to .DDS format.
What I can't figure out in Terragen is how to change that Field of View on the camera. Perhaps someone with more Terragen experience can do that.
As to what I use...what, you want me to give up my trade secrets before I even get to open my site?
Just kidding. It really doesn't matter becuase I'm only going to be selling to those people who can't make their own, don't have time to make their own, or simply just don't want to hassle with it. Hell, I may open the site and not sell a damn one of them. Luckily, it's only a hobby anyway
So, to answer your quesiton I use Bryce 5.5 (DAZ|3D), Adobe Photoshop Elements, DDS Converter 2 and GoCubic (for the QTVR's). Most of the models I'm using in the Skycubes I have purchased from the DAZ|3D store as well.
Hope that helps.
--formally FPSCreators--
"Trust no one" --Deepthroat (X-Files)