John Murray (1898-1975) was one of the great Reformed exegetical-systematicians of the 20th century. John Frame once remarked that one hardly needs any other books for the study of systematic theology than the four-volume Collected Writings of John Murray. You can listen to MP3s of Murray lecturing on systematic theology here--though the recording quality is quite bad.
Despite Murray's extradordinary accomplishments, Jay Adams writes that “What Murray had done exceedingly well, [Robert] Strimple did even better. . . . While Murray was a brilliant exegetical theologian, students commented that his teaching in the classroom left much to be desired. From the old Scottish school, he inherited and used methods that not only failed to communicate but also often left students cold. Strimple brought a different and more vital teaching method to classes that gave new life to and love for the study of theology (and of even more importance—for the study of the Bible).” (Jay Adams, “Westminster Theology and Homiletics,” in The Pattern of Sound Doctrine: Systematic Theology at the Westminster Seminaries, Essays in Honor of Robert B. Strimple (2004), p. 262.
Now Professor Strimple--recently retired-- is putting his systematic theology lectures and teaching materials from Westminster Seminary unto CDs. The first class--Salvation in Christ-- is now available in a 50-CD set. It might seem a bit pricey, but it’s a pretty good deal in comparison with the cost of tuition!
For those who’d rather have seminary-level lectures for free, check out the Biblical Training website--especially the Leadership Education section--run by our friend Bill Mounce (bestselling Greek textbook author turned pastor).
Finally, for those who want to earn a master's degree through accredited seminaries with online programs, see Reformed Theological Seminary's Virtual Campus and Covenant Seminary's Access Program.