Are there any other open-source-ish economics texts?
Check out the texts listed at the Economics Network site. (Quantum Microeconomics is listed under “Introductory–Principles of Microeconomics” and “Intermediate Microeconomics”.) For an open-source micro text that covers even more stuff than Quantum Microeconomics with Calculus–and is written by an economist much smarter than yours truly–check out Introduction to Economic Analysis by CalTech professor R. Preston McAfee.