Why would a person have a craving for the taste or smell of
eucylaptus, camphor, menthol, clove, or all of the above?

Hello geri-ga,

An aromatherapist who treats a friend of mine gets him to smell
various oils and indicate the ones he is most drawn to.  These are
then used in his treatment.  I started my search by looking to see
whether this idea could be linked to your cravings.

An article in the Calgary Sun on December 22, 2000 quotes Anita Kraft,
an aromatherapist, “People will like the smell of certain oils," she
says, "and often, their bodies are requiring the healing effects of
that oil at that particular time."  She herself developed a craving
for lavender when she had a nervous system problem.  She then found
that lavender oil is reputed to balance the nervous system.
http://www.canoe.ca/LifewiseMirrorsBodyMind00/1222_aroma_sun.html

I wonder if your body is giving you a similar message?  All the scents
you mention can be found in essential oils that are used in
aromatherapy.

The Pioneer Thinking site has the following information about the
properties of these oils:
Eucylaptus -  Promotes healing, also used specifically for nasal and
chest congestion, asthma, sore muscles, cuts and abrasions. 
Apparently it is also good for explosive emotions
(http://www.essential--oils.co.uk/eucaltyptus.htm)
Camphor – This is used for nervous tension, and also for bruises,
burns, spots, ulcers, wounds, muscular aches, colds, fever, flu, also
said to increase energy.
Clove bud - Promotes healing, and positivity, also used for
toothaches, sore throats, mouth inflammations  (Needs to be avoided in
pregnancy and not used on children)
http://www.pioneerthinking.com/aromam-o.html  Also used for fatigue
and melancholy http://www.essential--oils.co.uk/Clovebud.htm

Menthol is a major constituent of peppermint oil, which is said to
sharpen the mental functions and memory and help with feelings of
apathy and helplessness (extra info from
http://www.essential--oils.co.uk/peppermint.htm), and is also used for
gas, sore throat, digestive tract problems, stomach ulcers, nausea 
http://www.pioneerthinking.com/aromap-r.html

You might like to explore getting some aromatherapy sessions based
around these oils, and see what this  does to your general well-being.

IMPORTANT: Essential oils should never be taken internally, except
under the guidance of a qualified aromatherapy practitioner.

Search strategy on Google: 1. aromatherapy, craving  2.  essential
oils, properties

I wasn't able to find any clear answer to your question, but I will
include some links that hinted at answers.

Google search: craving camphor
About Absinthe
Information on the vintage drink extracted from a variety of sources
Author listed only as "Chad"
http://www.tower.org/kitchen/cellar/absinthe.html

In relation to Van Gogh's addiction to Absinthe:
"Statements in van Gogh's letters and from his friends indicate that
he had an affinity for substances with a chemical connection to
thujone; the documented examples are camphor and pinene. "

CLINICAL TOXICOLOGY REVIEW
Clinical Toxicology Review is published monthly by the Massachusetts
Poison Control System
Vol. 18, No. 4,January 1996 
Also in regards to Van Gogh and Absinthe (an alcohol based substance
made from wormwood extracts):

"Van Gogh's reported pica for paints and his craving for camphor and
turpentine are thought to have represented the effects of chronic
absinthism, causing him to seek out the ingestion of terpenes of any
sort.(1)"
(referenced footnote"
"References (First author only)
1. Arnold, WN: JAMA 1988;260:3042-3044. "

Perhaps someone with more experience with chemical issues, or
addictions can add to this.

Mother911-ga

sorry the second link should have been
http://www.maripoisoncenter.com/ctr/9601absinthe.html

placed like this in the comment:

CLINICAL TOXICOLOGY REVIEW 
Clinical Toxicology Review is published monthly by the Massachusetts
Poison Control System
Vol. 18, No. 4,January 1996
http://www.maripoisoncenter.com/ctr/9601absinthe.html  
Also in regards to Van Gogh and Absinthe (an alcohol based substance
made from wormwood extracts):