I've created an open-source chemistry dictionary which can be integrated into Microsoft Word and OpenOffice.org Writer.
It can be downloaded here:
http://www.chemspy.com/chemistry-news/open-access-organic-dictionary.htmlIt is fairly organic-heavy, but should be applicable to all disciplines. It currently only employs US spellings but UK spellings are an upgrade I am looking at with priority.
I hope my fellow chemists may find this useful.
-AA