Word counting questions almost always lead to statements about its impossibility and/or uselessness. However, if you use TeXShop there is an engine for counting words (texcount) in the ~/Library/TeXShop/Inactive/texcount folder. Drag either of the engines out of its folder into the Engines folder, and you can use that to count words. To use it, choose it as the engine and then "typeset" the document. It will open a web summary of the counts and how it did it. It works off of the latex source, but is pretty good for most things.
From comp.tex.macosx
There's also a
texshopfull.engineintexcount. Adding onlytexcount.engineor both engines toEnginesdoesn't produce any HTML files for me, even after restarting TeXShop. I wonder if I need to tell something else to look for them.