Okay, well I am not sure which applications this works in... it may just be Adium, but if you press Ctrl + Command + Down Arrow... whatever text you have in the text box will disappear and a down arrow will replace it at the end of the box. You can then type whatever you want send it and carry on, but when you click the arrow the text is restored so you can send it at a later time. It's kind of like saving what you're going to say until you say something first just so you don't forget or copying it all and pasting it later... kind of hard to explain. I use it a lot in instant messaging though. I stumbled across this just by hitting the keyboard with my binder and I tried to re-create what happened. Anyways, try it out and see what I mean...
