I have whipped up a quick I7 syntax coloring module, for the BBEdit/TextWrangler editors (on MacOS).https://github.com/erkyrath/BBLM-Inform7/downloads
The I7 parsing is off the top of my head, so it may be wrong in some situations. Let me know. It skips quite a few features of the standard IDEs. Notably, it colors an I6 inclusion as a single block, rather than trying to syntax-color the I6 in its own right.
(Vimes is in the process of porting the standard syntax colorer from the Mac IDE into the BBEdit framework. But I'll let him report on that. :)