YourStop is GTFS based and multi regional. It currently runs in Baltimore, Boston, Toronto, Thunderbay, UK West Midlands and Ireland and can easily be extended to other locations.
I plan on writing short tech articles on various aspects of the system, these will appear on the yourstop facebook page at
https://www.facebook.com/YourStop-485305331845608/
This post
https://www.facebook.com/permalink.php?story_fbid=809794042730067&id=485305331845608
isn't really a tech article but does discuss the GTFS implementation in Ireland and West Midlands in the UK. Discussion is welcome, particularly on the FB page.