efficiently viewing Unix timestamps as dates

[Ted Zlatanov]

Is there a mode to view (not convert!) Unix timestamps as dates?

It needs to be efficient because these are large files on remote
systems, and they are read-only so I can't modify them.

Ideally I would customize the time format and then turn this on as a
minor mode.  So I thought I'd ask if this already exists before I start
coding :)

Thanks
Ted