http://www.planetannihilation.com/terragen/delphi.shtml
Few notables:
Terrain Browser
Terrain Browser is a program for displaying a list of Terragen terrains in thumbnail form. It includes terrain info and terrain preview windows. The preview window has options for adjusting the water level, displaying a 3D relief effect, and drawing water level changes in real time.
The browser also includes the option to delete a selected terrain.
The program is not quite finished but unfortunately unless I decide to rewrite it from scratch it won't ever be, as I've lost the source code for the main unit.
Terrify
Terrify is a program for converting terrain data between Terragen (TER), RAW and Windows Bitmap (BMP) formats. Also included in the zip file are 6 small standalone conversion programs.
Terrain View 3D
Terrain View 3D is, oddly enough, a 3D terrain file viewer for Terragen terrains. It includes options for terrain smoothing and lighting. Press F1 in the program to get a list of keyboard and mouse commands.
To use this program, just run it. You will be asked if you want to associate Terragen terrains with the program, so then all you have to do is double-click a terrain. It uses OpenGL for display, so if you have a decent video card, it will run great. I made this program using nothing but the Windows API.
Slope Analyzer
Slope Analyser is a program that displays pixel brightnesses along a line, diplaying the data in graph form. It is designed to be an easier way to visualise Terragen height data.
And my favorite is probably...
RGB Colour Picker
RGB Colour Picker is for picking up a colour from the screen. You can also 'mix' your own colours, by moving the sliders. The program gives colour output in hexadecimal HTML format and decimal Windows format.
The program includes options to sample 3x3 and 5x5 pixel averages, which is useful for picking up a colour from a dithered image.