Mixcloud - The “Follow” button changes to “Follow back” if the user is already following you.
Tumblr iPhone app - If you swipe the edit button to the left you can create a new text blogpost. (and if you swipe it upwards you can make a photo blogpost)
/via Robin van ‘t Slot
Twitter - If you follow a “Tweet” link when not signed in, the Twitter dialog window allows you to sign in & Tweet in one action.
/via Rich Dooley
Tumblr - When someone you follow re-blogs someone you don’t, a mini follow button appears inline with the post.
/via Brian Jacobs
eBay - When viewing an item that you’ve purchased in the past, the button changes from “Buy It Now” to “Buy another.”
/via Jason Seney
Google Maps - When zooming in to the maximum, the zoom in button merges with the street view button indicating that the next zoom level is with street view.
/via Toby Adams
Gmail - While in the inbox, the Compose button is red. Then when composing an email, the Sendbutton is red instead.
/via Joe Sparano
Amazon - When not on the Amazon homepage, hovering over the logo will make it look like a button and show the word “homepage” under it.
/via Lior Fisher
CNNArabic - Even the “Play” button has direction from right to left.