Ok, I've taken my first stab at a mono-compatible tool. Turns out I couldn't get MonoDevelop to build my VB code for some reason... So now I've spent some time converting the most important bits of code to C#, and it looks like I'm able to compile and run under mono.
What I have at the moment is a command line tool:
Code:
monowordbuilder <file_name>[ -v][ -r <starting_rule> <amount>]*
Which outputs a number of generated words, either just the root word or the larger output which contains marks and branches (using the -v argument).
If you don't enter any rules at the command line, it'll use the defaults you've set up in the .wordo file using the StartingRule directive. If there are none, it'll default to generating the 'root' rule 100 times.
Oh, and I've no idea how to package it, so if anyone's able to help out there, that'd be great. The source code is available at github.