[aylad]

Ignoring what MaxieDM said (as though people can't tell you're casting a spell when red light comes blazing from your hands)... (stupid sarcasm, go away)

You can already do this, now that we have a spell menu. Use the menu to bind a spell to a key (look on the screenshot gallery for instructions to do this). Then (say you bound icestorm to key 1) type /bind 1 say Spirit of the North Wind, aid me now! and then whenever you press 1 to cast icestorm, you'll say blah blah blah automatically. I do it, and I think it's awesome.