A spell-checking feature would be really nice, I have no idea how this can be done but I've seen it on some forums similar to this one.
A imagine a "Check spelling" button that takes your text open it in a new window and underline your mistakes. We all make them.
The spelling on the internet is horrible, lets do our best to keep spelling somewhat good.
(By all means, get the important things done first, this is just a minor feature)