Visual Programming Book

Visual Programming by Nan C. Shu

This book gives an introduction to theory, and goes on to show many examples of visual/graphical computer interfaces to systems.

Examples include...

KAESTLE -- a graphic editor for LISP data structures
SEE -- "pretty printing" of C programs (in multiple fonts, with page titles, bold, italic, etc.)
Xerox Interlisp System
flow charts (old style, and structured)
NassiShneidermanDiagrams ''(...a strongly "structured flowchart," represented as nested boxes. Like "IF" is a box with a condition on the top, "false" code down the left half, and "true" code down the right half.)
StateTransitionDiagrams?
Tinkertoy -- "plug and play" coding of LISP functions; a lot like Lego blocks.
IBM's QueryByExample (QBE)
Pascal BLOX -- boxes with "jigsaw puzzle" connecters which restrict one to correct "structured flowchart" representations. (...but each nested code block jumps to another diagram, making it hard to see much of the program at once.)

...and the book covers a lot more systems than I've listed here.