Q by Mimicry Labs - Extension Cheatsheet
You can always find the shortcuts at:
Ctrl+Shift+Space: Add current page to queue
Ctrl+Shift+Right Arrow: Fetch next article in the queue
Ctrl+Shift+Up Arrow: Meh, lets read it later. Send it to the back of the queue and get my next article.
Ctrl+Shift+Down Arrow: Not worth keeping around. Remove it from the queue completely and get next article.