Another one of my “this is simple but I never remember it” posts: running aspell from emacs. Setup with

(setq-default ispell-program-name "aspell")

in your ~/.emacs file (from the aspell manual). Then use the standard emacs spelling commands:

• M-x flyspell-mode enables Flyspell mode, which highlights all misspelled words.
• M-x ispell spell-checks the active region or the current buffer.
• M-x ispell-message checks and corrects spelling of each word in a draft mail message, excluding cited material.
• M-$ (ispell-word) checks and corrects spelling of the active region or the word at point.
• C-g or X quits interactive spell checking. You can restart it again afterward with C-u M-$.

With a bunch more commands in the emacs manual