I am looking for studies, papers, reports, tests, etc, (either private
or public) on the tangible and intangible benefits of office "perks". 
Office perks being defined as something an employer does other then
compensation for its employees benefit, i.e. free office coffee, free
or subsidized catered lunches, bagels in the mornings, free sodas. 
"Perks" are not the traditional paycheck items like a car allowance,
insurance package, bonuses, vacations.  I am looking for studies that
enforce the notion that offering "perks" to employees ultimately
yields productivity and profitability for the company through a more
motivated/productive employee.  Ultimately, that it is in the
companies best interest to embrace the aforementioned employee
"perks".  Studies with graphs and/or charts would be best.  Also, I am
looking for studies that emphasize coffee and its positive effects on
workplace productivity/motivation.  (I need at least 3 studies)

This article might be of some interest, since it mentions coffee:

http://www.findarticles.com/p/articles/mi_m0DTI/is_9_28/ai_65283488

Thank you.  I will take a look.