Make A Pass
Update: I’ve made a new tool to generate Diceword Passphrases. Check it out!
Update 2022-04-10: I got tired of navigating to this page, clicking the button, then copying the password, so I made a handy bookmarklet to generate 16-character passwords with exactly 1 uppercase letter, 1 number, a dash, and 13 lowercase letters. Just drag the get random password bookmarklet link to your favorites bar and click! Here is the source script for the bookmarklet.
The following script generates a random password using the options you choose. The settings are similar to the ones found at WinGuides (thanks, Ryan, for the link!).