Something that had been bothering me for a while now was that whenever I went to change the dictionary I used to spellcheck in Firefox, it would list about 20 different variations of English, of which I only used 2. Looking in the Dictionaries list in the add-ons menu, there was only one of those packs listed, which I added manually. As it turns out, my installation of the hunspell-en package added every variant of English, and for whatever reason Firefox decides to include all of them. The easiest way to remove them is deleting the non-essential packs listed in /usr/share/hunspell. After a quick restart, they are no longer listed in Firefox.