A range of toilets, from low-tech to high-tech, in various parts of the world, including unusual facilities in two academic institutions

Low Tech   / Water and Labor Saving   /  Eastern  / High Tech   /  Unusual Academic    / Toilet Signage   / Links

Rural 5-hole family toilet, New York State, USA (no longer in use)
Ancient Roman military latrine (artist's conception based on ruins at
Hadrian's Wall, Housesteads, UK.) 
Pit Latrine, The Gambia, 
West Africa. Cover stone (middle) is replaced after use to keep flies out.
LEFT: Water recycling toilet, Japan. Handwashing water collects in tank, then is used to flush the toilet.

RIGHT: Water-saving hotel toilet, Switzerland, with separate buttons for large and small volume flushes

Flushmate (R), California, USA
High pressure tank allows effective flushing with a very small volume of water, like the toilets used in many airliners. 
Weighted Mens seat, Palermo airport, returns to Up position when not in use
Composting Toilet (Massachusetts, USA)  Directions say to add 1 cup of peat moss (in white container at right) after each use, then mix and aerate by turning crank at front 2 complete revolutions.  If compost becomes too dry (toilet paper visible) add water. If too wet (compost is muddy or claylike) add more peat moss.
Floor toilet, Elephant Island, India
Traditional Japanese Toilet, Tokyo
Washlet (R) Japan (instructions)
Washlet (R) sprayer in action. 
Restrooms at the Newton Institute, Cambridge University, UK are equipped with chalk boards, for mathematicians whose ideas can't wait.
Plumbing fixtures at Student Union Building, Northeastern University (Boston, Massachusetts, USA) are of ordinary appearance but emit peculiar screaming sounds when used. Screaming Toilet Movie

Most restroom signs indicate only the gender of the intended visitor without hinting at the nature or importance of the service provided.  These signs, posted respectively on the outside and inside of the restroom doors at an Irving gas station in western Massachusetts, USA, are an exception.   
Before and After restroom signs

See also  Bob Cromwell's Toilets of the World and the  World Toilet Organizatoin