What compound(s) have a melting point between -20 and + 5 degrees
Farenheit, and what is the latent heat of fusion for each.  Limit to
common industrial compounds.

seaweed,

i think $5 is bit low for a lot of groundwork some of the researchers
would need to do to answer your query.  Which by the way should be
quite readily available in Chemical Abstracts, I would not want to
plow through millions of industrial compounds to give you the list. 
Maybe some of the other researchers would have a handy software for
them to search through CA.  (the electronic version of CA database
requires subscription and your $5 does not even come close to the base
subscription rate 8-)....for your info and reconsideration.