Here’s the latest version of my quick-reply bookmarklet. It lets me reply to any URL now, not just tweet URLs.

Copy and paste the below as a bookmark, changing http://example.com/endpoint/?url= to your desired endpoint.

javascript:(function(){var endpoint='http://example.com/endpoint/?url=';if(document.location.hostname=='twitter.com'){var container;if(!(container=document.querySelector('.selected-stream-item'))){if(!(container=document.querySelector('.permalink-tweet-container'))){alert('Could not find tweet permalink. Are you sure a specific tweet is selected?');return false;}}var in_reply_to='https://twitter.com'+container.children[0].getAttribute('data-permalink-path');window.open(endpoint+encodeURIComponent(in_reply_to));}else{var in_reply_to=document.location.href;window.open(endpoint+encodeURIComponent(in_reply_to));}}())