For one of our visualisation assignments, we briefly used a terrain generating tool called Terragen (r), which is freely downloadable (for non commercial use) from http://www.planetside.co.uk/terragen/. Unfortunately, I'm not playing any d&d at the moment, so I' not sure how helpful it would be, but it makes it extremely easy to generate lifelike images of terrain. Hopefully, someone will find a use for it in their campaign.
Here's an example that only took a few minutes to create:
Here's an example that only took a few minutes to create: