Dial R for Reply от Nash Bridges

This is a browser extension that allows Github-like quoting. You select a text
on a discussion page, hit "r", and that inserts the selection as a quote in the
text area on the page.

In Firefox multiple quoting is supported. Select first chunk of text, hold Cmd/Ctrl, then select the next one and so on. Finally press "r" -- each chunk will be quoted separately.

So far only the following sites are supported:

• basecamp.com
• slack.com