Tell her you want to spend eternity with her... in a crypt. The website doesn't give any hints as to what the scent might smell like, but the description - "The smell of moss clinging to a marble mausoleum" - is evocative.
Looking for that perfect gift for the person who hates everything? How about something to scare the bejeezus out of your mother-in-law? Just want a treat for yourself? Then check out FEARnet's Gift Guide, packed with hundreds of hand-picked items, updated weekly with stuff you need, and stuff you didn't know you needed.