Double entry accounting is useful any time you have limited amounts of a resource and want insight into how it is used. You don't need to apply it as strictly a

Double entry accounting is useful any time you have limited amounts of a resource and want insight into how it is used. You don't need to apply it as strictly as accountants do -- very general categories and a random sample of transactions is fine for most types of analysis. The important part is that every unit of resource comes from somewhere and goes to somewhere. As long as you fulfill that property, you get powerful querying capabilities. Most recently I've used it to compare various means of acquiring more RAM for an operation (cloud offerings, incremental purchase, leasing large amounts, etc). One of the other benefits is that I can mix both "terabytes of memory" and "thousands of euros" in the same book, and exchange rates between the two also fall out of the equations.