Square - The QR code used to pay has the Square logo integrated into it.
GitHub - When you delete a repository, it has you type the full repository name to confirm the action.
via Eric Morris
OS X - Searching in System Preferences highlights the relevant sections. The more relevant the section, the brighter the light will be.
Chrome - When downloading a file that “appears malicious” Chrome asks if you want to keep or discard it.
/via Tee Jay Green
scri.ch - The 404 is a regular scri.ch drawing (you can draw on it and save it as a new drawing).