From the Firefox website:
Adds Aspell spell checking to the context menu. Left click in any text box and select AspellFox from the context menu. You can also select text in a text box and run aspellfox on the selected text.
You can get the extension here:
addons.mozilla.org/firefox/1022/
I wish that there is a spell check feature in the forum itself.
Nice, but why not simply learn to spell?
A
Agreed. But this extension can catch the typographical errors especially of people whose thinking speed is very faster than their typing speed and wanting to post an immediate response.
It can also help the non-native English speakers like me with the often confused words.
BTW, I never spelled Nietzsche correctly, no matter how many times I try. 
there there my friend , you could have just said freddy 
.
that could get rather annoying for the jews , just saying.
DDF 2 robo_sapien