Spell checker for web forms?

I found one called Spellify that comes close to the functionality I’m looking for, but can’t get it to work without errors, plus it’s based on Google’s dictionary and the users can’t add to it for common terms used in our community - it would end up getting annoying. I don’t want a solution where the user has to press a spell check button after they’ve typed, it should automatically underline as the user types, just like FF.

Basically, I just want something that does exactly what Firefox does - underlines misspelled words when a user types in a textarea field on our site - if IE would just build this into their stock browser already I wouldn’t need a solution for it :mad:. A popup box with suggestions would be nice, but not critical. I just mainly want the user to know which words they’ve typed are spelled wrong.

This looks like a nice solution, but only available for MS servers:
UltimateSpell - ASP.NET Spell Checker

Something like that for Nix servers would be great!