As you might know Twitter accepts more than just basic text. The service is UTF-8 compatible which means that instead of tweeting “I love you” you could just as well use “I ♥ you”. How did I do that? How can I add such symbols?
TwitterKeys is the answer to all that.
TwitterKeys is a small tool which provides you with a floating window with symbols you can use in Twitter.
Visit the TwitterKeys website and drag and drop a link to your Bookmarks Toolbar. After that, whenever you click on it, a popup will show up which will show the symbols as in the image. Just copy-and-paste the symbols you want to you into your Twitter update.