There is an astonishing amount of theological course material freely available online. In particular, two web sites have distinguished themselves by their course offerings. Covenant Worldwide make available 21 courses from Covenant Theological Seminary:

Covenant Worldwide is a ministry of Covenant Theological Seminary to distribute a foundational collection of its course materials to anyone, anywhere in the world at no charge. Our hope is that missionaries, lay leaders, alumni, educators, and students will draw upon these materials to nurture their walk with the Lord and to enhance their ministry to others.

Biblical Training, not associated with a particular theological college, make available at least 36 courses (additional courses are made available as they are funded), divided roughly into lay and leadership education. For example, John Piper offers a pastoral theology class (TH520) and Bill Mounce offers an adumbration of Greek (NT601).

It is well worth investigating their offerings.

HT: ESV Bible Blog