TheMadCharles, unfortunately I am not allowed to share those files, as they are copyrighted material. Someone would have to ask Team17 for their permission to make those files public.
You can use http://worms2d.info/WA_directory_editor to create new terrains based on existing ones. Make sure to use the same palette as the original files. SiD has already created a Tetris themed terrain.

As maintaining up to date list of terrains is bothersome, I would suggest to create a new category of files on TUS and create a simple xml/json list of terrain names + direct urls to files. A simple update to the module/separate program would query the list on regular basis and download new terrains.

this simple wormkit module allows you to use custom terrains without replacing the original ones
usage: put new terrain folder in Data/Level (for example: Domestic or Dino from WWP)

note: terrain lists and files are NOT synchronized in online multiplayer games! if you want to play online with your friends, ensure that you have the exact same terrains installed.

tested on steam 3.7.2.1, probably works on cd version too.
edit: updated to newer version - you can use now up to 127 terrains total

download: [attachment=1]
source code: [attachment=2]

examples:
- dinos from WWP
- domestic from WWP