Going to post something here to grant it some (re)visibility. There are several decent GPL spellcheckers out there (
phpSpell is a good example) but the developers aren't too interested in catering to VB because they are forced to buy a license to figure out how to integrate and support it, and meantime they're all running other boards (like phpBB or IPB) where it works already.
We really need to look into this. From what I can see by reviewing the numerous replies and discussions, is VB3's WYSIWYG editor is the primary bottleneck. All I know is, this is a perpetually recurring topic. Whomever manages to figure it out is destined for fame and fortune

.
An obvious solution might be for a few of us to pitch in and buy one of these guys a VB license. Right now they simply won't code for VB because they're forced to do it blindly.