After spending a good amount of time playing with WiX I have decided to start a GUI installation designer project for it. It's called (creatively enough) WiXGUI, and can be found on SourceForge.
If anyone is interested in helping out, feel free to contact me via here or my SourceForge contact page.
Right now I am just compiling a list of examples and usages to try and nail down the specifics. If anyone notices anything cool please let me know.
I will post updates to my progress as the tool evolves.
"Computers are useless. They can only give you answers." -- Pablo Picasso