The domain name michigan-terminal-system.org is owned by Jeff Ogden and is registered with MyDomain.com and MyDomain.com provides the name servers to support the domain. Registration fees are paid for one year and renew automatically (assuming that Jeff's credit card still works).
There are two sub-domains that are used: archive.michigan-terminal-system.org and www.michigan-terminal-system.org. They both point to the MTS Archive site. There is no additional charge for the sub-domains.
The MTS Archive site is currently a free Google Sites site, https://sites.google.com/site/michiganterminalsystem. The site was created by Jeff Ogden (email@example.com). Jeff Ogden, Gavin Eadie, and Mike Alexander are owners of the site. There is a 100 MB limit on the size of the site, so most large items are stored elsewhere and linked from the site.
Access to the Google site is controlled using the free Google Group "# (Pound Sign)". Jeff, Gavin, and Mike are owners of the group. Anyone can join the group. Members of the group may edit and contribute to the MTS Archive. The site is associated with both Google Analytics and Google Webmaster Tools.
Most photos and several videos are stored on Google's free Picasa Web Albums under the name "Michigan Terminal System Archive". Jeff Ogden is the owner. Anyone can view the albums. There doesn't seem to be a way to give Gavin and Mike edit access other than by sharing the account name and password.
Most larger non-photo, non-video documents are stored as Google Docs (now Google Drive). Jeff Ogden is the owner. Gavin and Mike have edit access. A modest fee is paid to get additional disk space (200 GB). This extra disk space is also available to Picasa Web Albums.
When the Google site was suspended during December 2010 a new interim site, http://web.me.com/mtsarchive/MTS_Archive, was created using Apple's iWeb and MobileMe. The MobileMe account belonged to Jeff Ogden under the name "mtsarchive". It was a free 60-day trial. The site went away when MobileMe went away.
The MTS Wikipedia articles are stored on Wikipedia. Wikipedia is a world of its own. No one owns anything or everyone owns everything, so ownership is not an issue.
Jeff makes a backup copy of these materials from time to time and plans to give copies of the backup to Gavin and Mike and eventually to the Bentley Historical Library at UM. The Bentley also captures the MTS Archive site in its University of Michigan Web Archive about once a year.