The gbmedspell project aims to provide an open source spell check dictionary for medical terms in British English for office suites such as OpenOffice.org and Microsoft Office.
This is very much a work in progress and as of the 27th May I'm about 50% of the way there to creating a first version. You can however download an alpha version of what I've done already and give it a test. When I release the first full version it should contain around 15,000 general medicine terms covering anatomy, generic & brand names of drugs, procedures and diseases. For now I have decided not to include acronyms as there seems an inexhaustable list of them within medicine that would soon swamp the spell checker.
gbmedspell is designed to work along side your current spell checker, not replace it, so many simple words will not be found within as it is expected your current spell checker recognizes them.