The main problem with that... there isn't any underlining available on the edit line. That would have to change. Besides, IRC is just for chatting. There isn't any more need for good spelling on IRC as there is on IM, where most people use shorthand "IM-speak" instead of typing out words anyhow. On a browser, spell checking makes sense because you might be filling out a resume or doing something else important. That just isn't the case with IRC. Besides, auto spell checkers dumb people down. You don't learn to spell if everything is done for you. You learn to spell by actually having to do so.
