[web.archive.org] has "Atheist Taxonomy: The Five Varieties of Atheists" by Lucia K. B. Hall. I've added a few categories, and I must note that they are not mutually exclusive.

• Nihilistic
• • Never gave it much thought
• • Don't care
• • Have other interests
• • (me) Too lazy to bother
• • (me) It is a waste of time
• • (me) Troll atheists
• • (me) Noble-lie atheists: religion as desirable as opium for the people
• • (me) Party-line atheists, out of believing some belief system or belonging to some organization
• "Mad at god"
• • (me) Mad at religion
• • (me) Proud atheists: a god existing would be a great humiliation
• • (me) Depressed atheists: how terrible one's life is
• Philosophical atheists
• • Logical ones
• • Emotional ones
• • (me) Religion-deficiency ones
• Scientific atheists: god as an unnecessary hypothesis. God is either very far off or else acts very mechanistically
• Reared atheists

What kind of atheist or agnostic might you be?