How about a spell checker when posting??

Just curious why we dont have one...

We don't have one because this is functionality which should be provided by the browser, rather than being something which all sites have to implement for themselves. This has the benefit that if you use a couple of words which aren't in the built-in dictionary a lot, you'd only need to add them to a dictionary once, rather than doing this again and again at every site you visit. The case goes even more strongly if you write in non-English languages.

And indeed, all modern browsers (Firefox, Opera, Safari, Google Chrome, SeaMonkey) include a spellchecker by default, and I believe that for IE there's at least a spell-checker available as an add-on, though why anyone would want to use that outdated browser in this day and age is beyond me.

I use IE. Is it no good? I was gona download Google Chrome...

Download, download, download!!!

Okay, I use a Mac and Safari - but we also have a PC laptop - download Chrome or anything else. Seriously. Sander is correct.

Then I shall....right this very moment!