ConTeXt comes with the extensive chemistry module PPCHTeX which allows the drawing of chemical structures and the typesetting of reactions.
PPCHTeX works with plainTeX, LaTeX and - of cause - with ConTeXt.
- PPCHTeX (general) by Pragma
- PPCHTeX documenatation by Pragma
- PPCHTeX mailing list
- PPCHTeX mailing list archive
Some other links:
- PPCHTeX structure database
- PPCHTeX FAQ and PPCHTeX FAQ in PDF(rather old)
- TUG Boat article on PPCHTeX by Hans Hagen and A.F Otten