My wife has a large collection of cashmere tops. I like to compile a
comprehensive guide on how to remove various types of stains on
cashmere:- coffee, lipstick, food gravy, softdrink... (the list goes on). 

Will pay handsome tip for comprehensive answer. Thank you.

i have seen my grandmother use a coat of lime salt and butter to
remove stains first goes a coat of lime then a coat of salt water and
then a light coat of butter then she uses detergent to wash all this
off after sun drying but do be carefull it works for her but ....

Everything I have ever learned about cashmere care says to never leave
it near heat or in the sun.  Remember, this is wool and like any wool
it will lose it's shape and stretch anywhere that the fibers have been
shrunken by heat.  Spot cleaning tends to change the texture/stretch
in that area.  When using detergents to hand wash cashmere be sure to
dissolve the detergent completely before adding garment and use cool
water - no wringing or squeezing.  Here are a few suggestions and
links for you:

General stain removal:
http://www.allola.com/cashmerefaq.shtml
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Chocolate can oxidize any fabric to cause a permanent stain. Cashmere
wool is best sent to a professional cleaner for spotting & cleaning.
While enzyme cleaners are often recommended for chocolate stains on
fabrics, enzymes should not be used on wool. A solvent cleaner such as
rubbing alcohol, denatured alcohol, or dry cleaning fluid can be used
for spot cleaning wool. Test first in inconspicuous place for ill
effects. Do not use bleach on wool or hot water.
http://doityourself.com/info/qnacleaning6.htm
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For detailed care of cashmere from the Cashmere and Camel Hair
Manufacturers Institute
http://www.cashmere.org/english/garment.htm
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Dry-clean woven cashmere when the fabric is dirty or stained. To
remove dust, lint, or pet hair, put the item in the dryer on the
air-fluff (no heat) setting for 15 minutes. For cashmere knits, hand
wash with a mild detergent, such as Woolite, in cold water; lay flat
to dry.
CARE TIP: Spot-cleaning can ruin the texture of cashmere knits;
instead, dry-clean them.
http://www.realsimple.com/realsimple/content/print/0,22304,679640,00.html
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Cashmere garments should be handwashed in lukewarm water with soap
flakes or liquid soap. Care should be taken not to rub or twist the
garment as this may cause pilling.
After washing, rinse the garment in cool water until all the soap is
removed, squeezing gently without wringing. Squeeze away excess water
in a towel.
To dry, leave the garment to dry naturally away from direct heat and
sunlight. It is important not to spin or tumble dry. When dry, iron
lightly on a cool setting using a damp cloth or steam.
http://www.eribe.co.uk/cashmerecare