Pocket (iOS) - After copying a URL, opening the Pocket app will automatically prompt you to save the content.
/via Myles Tan
Google URL Shortener - After shortening a link the shortened link is automatically selected.
Coda - When ordering and choosing the amount of copies, the word “copy” after the inputbox changes automatically to the correct grammatical form.
YCN - Online competition submission form allows you to copy entry details from the previous entrant that you’ve entered.
Adium - If have a URL copied to your clipboard, Adium suggests this automaticly when you want to insert a link.
Mac OS X - When doing a calculation in Spotlight, Cmd+C copies the result without having to select it.
Chrome - After you copy a URL from the navigation bar, it automatically adds http:// in front of it when you paste it somewhere else.