FringeLanguages

I don't mean this pejoratively, but some languages are more on the fringe than others. Python is actually a bit on the fringe. I'd like to hear about languages whose usefulness exceed their popularity. -- SteveHowell

The only interesting speed factor for languages (as opposed to code written in them) is how much they slow down the programmer on his journey from problem to solution. -- Eric Naggum

A+ -- A descendant of APL (a mostly-mainframe old language with its own character set), developed by Morgan Stanley because APL's matrix manipulation is so powerful. I wonder if they considered Numeric?
Boxer -- is the first example of a "computational medium" for real people, not just for computer experts, created by Andrea diSessa. -- (JS)
Euphoria
Forth -- isn't a computer language, it is a cult. Write once, read never (JS)
HaskellLanguage
Lisp -- is the most powerful and misunderstood language, too abstract for CP4E. (JS)
Logo -- Still a great education language. With objects it would be the best CP4E. (JS)
Pike
Rebol
RubyLanguage - a very object oriented language with some Perl influence
SchemeLanguage -- for education only (JS) - also a popular research language, and a less confusing descendent of Lisp (WF)
Smalltalk
Squeak -- Smalltalk for kids (JS) - More than just for kids, Squeak is rapidly becoming a full featured Smalltalk (WF)
Suneido
ToonTalk -- A completely graphical animated programming system for kids. Bammer the Mouse uses his hammer to combine things (JS)