Common requirements:
I have identified common requirements/patterns for the "dialog" concepts I came across.
- OK and Cancel buttons
- Close icon in top-right corner (same action as "cancel"?)
- Hitting "escape" closes the prompt (same action as "cancel"?)
- User can move popup around using drag n drop
- Confirmation dialog must be enforced
- by ticking a checkbox
- by typing text
- by captcha-like process
- etc..
Mockups
I have "translated" to mockups some of those fully designed & live examples
mentioned in the question & added some of the concepts from the "common requirements" mentioned above.
Feel free to add your contribution in an additional answer. Thanks.
Mockups of basic dialogs

download bmml source – Wireframes created with Balsamiq Mockups
Mockups of dialogs with "checkbox enforced confirmations"
Enforced confirmation means that the user do an additional action - tick a checkbox in this case - to reach the next step.

download bmml source
Mockups of dialogs with "text-box enforced confirmations"
Enforced confirmation means that the user do an additional action - by entering text in a text-box in this case - to reach the next step.

download bmml source
Mockup of "complex dialog"

download bmml source
Related
https://github.com/hubspot/vex
http://codepen.io/cupofjoakim/pen/wEkag
http://codepen.io/matthewbeta/pen/rwhyo
http://codepen.io/adventuresinmissions/pen/nrhHF
http://codepen.io/nodws/pen/vELwJz
http://codepen.io/kushalpandya/pen/qhzwA
http://tympanus.net/Development/DialogEffects/
http://tympanus.net/Development/ModalWindowEffects/