Twitter - Characters exceeding the 140 limit are highlighted in red.
/via Simon van Woerden

Twitter - Characters exceeding the 140 limit are highlighted in red.

/via Simon van Woerden

Tweetbot - When replying to a tweet, swipe down to see the original tweet and author.
/via Kevin S.

Tweetbot - When replying to a tweet, swipe down to see the original tweet and author.

/via Kevin S.

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

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

Twitter - iOS app gives feedback in the status bar when you Tweet.
/via Sebastian Hall

Twitter - iOS app gives feedback in the status bar when you Tweet.

/via Sebastian Hall

Twitter - When submitting the same tweet twice, an error message is shown.
/via Sindre Sorhus

Twitter - When submitting the same tweet twice, an error message is shown.

/via Sindre Sorhus

Twitter OS X - Replaces time of the tweet with actions on mouse over.
/via Oldstrech

Twitter OS X - Replaces time of the tweet with actions on mouse over.

/via Oldstrech

Twitter for mac - After typing the first few letters of a word, pressing the ESC key will show a list of words that starts with those letters.
Edit: This is a native feature of OSX and works in some other apps as well. 
/via isseykun

Twitter for mac - After typing the first few letters of a word, pressing the ESC key will show a list of words that starts with those letters.

Edit: This is a native feature of OSX and works in some other apps as well. 

/via isseykun

Twitter for Mac - After installing the app, right click on any text in Mac OS X to see a tweet option.
/via Brendan Lee

Twitter for Mac - After installing the app, right click on any text in Mac OS X to see a tweet option.

/via Brendan Lee

Offcial Twitter app for iPhone - Dragging down the whitespace of reply screen shows what tweet you are about to send reply.
/via Lowply

Offcial Twitter app for iPhone - Dragging down the whitespace of reply screen shows what tweet you are about to send reply.

/via Lowply

Twitter - Text bubble hover new tweet icon

Twitter - Text bubble hover new tweet icon