I am sure you have come across plenty of applications that offer to show customized smileys on your Facebook chat. The issue is, if your friend does not have the same application installed on their profile they will not be able to see the custom chat smiley you are using. And most of these custom chat applications are malware or spyware in disguise. You can never trust them.
Is there any way you can use custom smileys as you wish on your Facebook chat and let your friends see it without having to install a Facebook app? Yes, there is. Facebook now allows you to use profile pictures as smileys in your Facebook chat. How do you do it?
Go to any Facebook user or page url and copy the I'd and come back to your chat window and put them in double brackets. The profile picture of that person or page will appear as a smiley. For example if you want to use "xyz" profile picture as a smiley, go to that user's url. Go to www.facebook.com/profile/xyz or www.facebook.com/profile/687659018 and copy the profile id. In this case copy xyz or 687659018. And paste it into your chat like [[xyz]]. This will enable you to use that person's Facebook profile picture as a smiley icon. You can also use profile pictures of pages as emoticons or smileys. The only catch here is that if the page is automatically created by Facebook from wikipedia, then you cannot use it as an emoticon. This is also a great way to share information about people and pages because when your friend who receives the emoticon hovers the cursor on the image he will see a pop up with information about that person or the page. I am sure Facebook will integrate this feature soon to status updates. Till then have fun converting people into emoticons.