If you're worried about humans picking the words - I use watchout4snakes. Get about 10 random words, and pick 4 or 5 that make a vaguely intelligible phrase. I don't know the size of their dictionary but my random 10 just now included theorem and pedantry.
Where good password rules (i.e. none) are enforced, I use correcthorsebatterystaple. Where bad password rules are enforced, I use correcthorsebatterystaple1!. This means if I remember my password, but can't remember the ruleset, I have a 50/50 chance of getting it right first time.