I've finally gotten some notes together regarding some of the
different mounts available to me here in North America. I've
placed this information at:
http://stereo.thurstons.us/content/
and will provide some of it here for immediate (and archival) use.

In the 80x140 mount selection, avoid the new Holga mounts!
Their square apertured mounts are spaced at 65mm and their
panoramic apertures are spaced at 66mm. This is going to either
require wicked eye-gymnastics, or force everything in front of
the window. The internal structure of the mount also prevents
free motion of the film chips. They might be a quick and dirty
way for someone to "mount" images from their pinhole-holga, but
the resulting images will be unviewable.

Also in the 80x140 mount selection, the newer 3D World mounts
have 53mm apertures! If you like your apertures large, this is
an extra millimeter over what the older mounts were and three
more than the traditional cardboard mount offers. Even though
they are no longer marked as such, they are still spaced at 62mm.

If you have information about common mounts that I'm missing, let
me know and I'll try to find space for it. If there are
editorial or technical problems with the content, please let me
know _off list_ and I'll try to correct them. If you have
information about mount formats currently used in other parts of
the world, I'd love to know that, too :)

John Thurston
Juneau, Alaska