If you love making natural perfumes, or are just interested in the essential oils, flowers, resins and plants involved in the process, you may find these links (from WhiteLotus aromatics) worth a gander:
A Guide to Medicinal and Aromatic Plants
A history of the use of incense in divine worship by Edward Godfrey Cuthbert Frederic Atchley
A Small Guide to Nature's Fragrances
Capacity and Volume Conversion Tables
Centre for International Ethnomedicinal Education
Chirality and Odor Perception
Citrus Oils
Culpeper's British Herbal
Database of Herbal Information
Essential Oil World Map
Flavors...