As you all know, external plugins are meant to facilitate manual exploitation of issues or anything you would do "externally" to OWTF.

This issue is to list the following useful resource, under the relevant XSS external plugins, to expedite building manual XSS PoC exploits to demonstrate the impact ASAP:
http://www.xss-payloads.com/index.html

(thx to @galadrim for the suggestion :))