If you have a formal systems bent, as I do, you might enjoy "Algebraic Models for Accounting Systems" (http://www.amazon.com/Algebraic-Accounting-Systems-Salvad

If you have a formal systems bent, as I do, you might enjoy "Algebraic Models for Accounting Systems" (http://www.amazon.com/Algebraic-Accounting-Systems-Salvador-Rambaud/dp/9814287113 http://www.amazon.com/Algebraic-Accounting-Systems-Salvador-...). "This book describes the construction of algebraic models which represent the operations of the double entry accounting system. It gives a novel, comprehensive, proof based treatment of the topic, using such concepts from abstract algebra as automata, digraphs, monoids and quotient structures." Think of it as a primer for building yourself an exceedingly awesome and utterly-unnecessary Haskell-based QuickBooks.