Here it is, followed by some examples and some example-worlds.
They're all in the zip-file which you'll have to extrude.
Update: I've just created an interface for you guys
Now, it'll be easypeacy to build your own terrain.
I just uploaded a version which generate smoother textures, still if you want it to be perfect, you should use a program designed for generating heightmaps and textures.
Features:
Create terrains with collision detection.
Create random terrains(I'm using the diamond-square algorithm).
Automaticy generate a suitable texture for the terrain.
Use heightmaps(grayscale) to generate a terrain.
Use your own textures.
The functions and the variables are automaticly added to the a2c.
This is the same program i used to create the terrains in this thread:
http://www.alice.org/community/showthread.php?t=4102
You'll have to have framework.net installed in order for this to work. In some PCs, it's installed and in some it isn't, so please try it before download. Im pretty sure that if you get an error, it's because you haven't framework.net, or else you could try to run it as administrator.
Link:
http://www.microsoft.com/downloads/d...displaylang=en
If you want the sourcecode, just ask.
Tell me what you think and remember to report bugs.
By the way, you should not use a heightmap with a size larger than 150x150. Alice doesn't like too much geometry
Since the complete terrain generator pack is some random palce in this soup of posts,
I've placed a link to it here 
The pack contains the terrain buider, the random heightmap generator and the heightmap texturer.
http://www.alice.org/community/showp...0&postcount=18
Here's the newest version, The Terrain Builder v2.1.1
http://www.alice.org/community/showp...4&postcount=52
I removed the Advanced version since it's messed up...
Have fun :]
~Zenteo Xero