Someone had asked me about shape notes. There are actually several shape styles, but the one I refer to is the 7-shape system. Information on shape notes can be found at Christianity - Shape Notes Top Links. This site has a load of links regarding shape note singing.
If you take a look at any of the files here you can get the idea. Each note of the scale has its own particular shape (Do is an equilateral triangle, Mi is a diamond, etc.).
There are still a few publishers who sell hymnals in this style, most notably Howard Publishing, publishers of Songs of Faith and Praise.