Just a quickie. This didn't take a lot of effort. Took something like RobA's mountain tutorial, then used a burn tool to hollow out a crater at the top. Messed a bit with the side, and added a low-depth noise bump map, then created a bump map from the gray-scale image.

Added a second layer of colors for the lava with yellow and oranges and reds blended and blurred a little.

I can provide a more detailed process if requested... but it's far from perfect, just a quick test to see if the concept works.

Click image for larger version. 

Name:	quick volcano.jpg 
Views:	87 
Size:	4.1 KB 
ID:	4640