Built in Python using Amazon, eBay, and Facebook APIs, PricePoint researches and recommends e-commerce arbitrage opportunities. PricePoint helps me find, price, and sell ~$xxk each year of books and other inventory to keep the student loan monster at bay.
Code here offered as example of book pricing from Amazon sales rank and listed price. Focus is on efficient allocation of capital in a conservative fashion.
Most of the system focuses on identification of products sold below the target prices determined by this code and other programs like it.