Came across Raspell, a Ruby binding for the Gnu Aspell spell-check engine.
Docs: http://blog.evanweaver.com/articles/2007/03/10/add-gud-spelning-to-ur-railz-app-or-wharever
Support: http://rubyforge.org/forum/forum.php?forum_id=13988
Tutorial: http://deezsombor.blogspot.com/2005/08/how-to-build-ajax-ed-spellchecker-with.html
