In Aquamacs in flyspell-mode, when flyspell flags a word as misspelled, I can right-click to add the word to my dictionary if it is in fact correctly spelled.
In GNU Emacs on OSX, when flyspell-mode highlights a word it thinks is misspelled, how can I add the word to the dictionary? Looking at the documentation, I do not see a function like flyspell-learn-word or ispell-add-word-to-personal-dictionary.
The function you are looking for is flyspell-correct-word-before-point. By default it is bound to the keys C-c$. Move your point to the incorrect word and execute the command. You will get a popup-menu with possible corrections and an option to save the word to you dictionary.
If you want a single command to save the current word, this is what I was able to extract from flyspell.el
(defun my-save-word ()
(interactive)
(let ((current-location (point))
(word (flyspell-get-word)))
(when (consp word)
(flyspell-do-correct 'save nil (car word) current-location (cadr word) (caddr word) current-location))))