Samkhya - wikipedia page
Samkhya Philosophy - short but readable intro based on Worthington's 'A History of Yoga' (1982), explains the Samkhya premise on Prakriti and the Gunas.
SAMKHYA YOGA revisited - a well-written essay providing a brief history of the Samkhya Yoga movement from its creation until its demise
Samkhya and Vedanta - short essay on Samkhya, and contrasts with the Vedanta teachings of Ramakrishna and Vivekananda.
SAMKHYA ("enumeration") - short basic intro on a no-frills page
The Six Systems of Vedic Philosophy - Sankhya - Nontheistic dualism - quite a detailed coverage, from the ISKON (Hare Krishna) site. A faint undercurrent of religious polemical bias ruins what would otherwise be an excellent coverage.
Hurqualya - philosophical essays in Spanish and English by Miguel Iradier, combining Samkhya, cognitve sciences, biology, non technical physics, mathematics, theory of time, health, and the experimental study of the pulse.
Platonic Epistemology and the Nature of Philosophical Activity: A Comparison With Indian Philosophy - by Marc Fellenz
"Demonstrate(s) that the epistemologies of both the Platonic and Samkhya-Yoga systems incorporate the knowledge revealed by experiences originating in internal consciousness, that both systems present the philosophical activity as the means to recovering these experiences, and that both hold that this activity is a necessary one for man, given his condition."