All done in Photoshop CS3...although gimp will produce essentially exactly the same stuff.
All off these (except the village - which is a blatant homage to zombie nirvana) were created using already created elements and textures, brushes etc I found on the net, so in some ways they are a bit of a cheat. However I always layer up elements and amend them/add bits/re-texture or shadow etc so what you are looking at is effectively a massive composite of things.
Using the ice as an example - its in several layers:
1. Bottom layer is a water texture I think I got from
http://www.cgtextures.com.
2. Above this is a snow/ice layer I got from the Dundjinni forums
3. I applied a layer mask to the ice layer, meaning I could non-permanently remove bits of it (my very favourite bit of Photoshop)
4. I found a cracked brush for Photoshop on the internet (can't remember exactly where but google will help), I do remember it wasn't quite what I was looking for so I made 1 massive brush stroke of each crack in Photoshop, aded and subtracted black and white until I was happy then saved it as a custom brush.
5. With a layer mask switched on, if you paint black onto it the painted bits become transparent, so I just painted the cracks on until I was happy.
6. Once I knew where the cracks would fall I went back to the water layer and used the dodge tool (effectively a highlighter) to tweak the highlights in the water.
So you can see although I blatantly borrowed the main elements there was considerable tinkering and playing aroudn tog et the effect I wanted. Actually it got more complicated than that as Neo who was running the game wanted the ability to add new cracks wherever he liked - but we won't go into that...
Motion on the train was made with judicious use of a motion blur filter in Photoshop
Best resources I've found for textures and elements are:
http://www.dundjinni.com
http://www.cgtextures.com
http://rpgmapshare.com/
But Flickr, deviantart,
http://www.sxc.hu and plenty others are good sources of inspiration.
Hope that helps, btw if you haven't already check out the EoA maps netbook in the library, I added lots of little Photoshop tips and stuff while I was making it, although some of the maps are really old and slightly embarrassing now....
Cheers
Lostboy
"I had a dream, which was not all a dream.
The bright sun was extinguish'd, and the stars
Did wander darkling in the eternal space..."