Hello,
If you're designing Swiss chalets and structures like freeway bridges that will look better with an Alpine mountain range in the background, you might be interested in these tutorials called River Canyon, using PD Howler 9.5:
http://thebest3d.com/slideshow9.5/myrivercanyon-1.1a.jpg
what started it all - the original River Canyon tutorial by Dan Ritchie
Deep dive tutorial series:
part 1 - elevation maps
part 2 - exporting terrain resources
part 3 - coloring parts of the terrain
part 4 - adding a snow storm
part 5 - erosion and sediments
Adding a fancy title
Adding a different sky
And if you're building the lost city of Atlantis: taking it under water
Many techniques seen here can also be used in Photoshop and other tools that support the use of images as 3D elevation maps. Sure, some will have extra features, such as help with erosion and sediments to make it look for interesting, but in the end, they're tools and techniques. Learn them and then add your special secret ingredient: your imagination and creativity.
Hope this helps.
-Philip