Google Docs - Pressing ⌘+s (ctrl + s) the first time will save the document in the interface, while pressing it again will open the default browser dialog to save the page to your hard drive.
/via Gregory Koberger
Kickstarter - After filling out a survey (for selecting pledge awards, providing address, etc.), the site gives you 10 minutes to edit your responses. This works even if you exit the site and return.
/via Paul Robertson
Gedit - When trying to close an unsaved document in Gedit a dialog tells you how much work will be lost based on the time since the document was saved.
Path - If you forgot to add one of the three requirements while uploading a photo on Path for iPhone, the buttons bounce as you tap on Save.
OSX - Hitting “Esc” chooses Cancel, hitting “Return” chooses Save, hitting “D” chooses Don’t Save. Allows you to control this menu without using a mouse or trackpad.
/via Andrei Herasimchuk