This site has two important aspects to it. The gaming portion and the writing portion. e.g. chat, forums, PM's, etc.
I think that a spell check mechanism would be a very valuable tool for PM's and the forum. I can't tell you how many times I read a post and have to make an effort to interpret what is written. I know that there is, currently, a tool that hi-lights a misspelled word in red. Regardless, I think that a spell check would be a very valuable and utilized tool both for the writer and the reader.
Thanks