Happy feast of Saints Basil the Great and Gregory Nazianzen! You’ll find some great links on Gregory here. You’ll find an audio file of Yours Truly babbling about both men here (scroll down to St. Basil).
For affordable, accessible reading, try these, one and all:
And, of course, you’ll meet both men in the pages of my book The Fathers of the Church.
UPDATE: The awesome Jeff Ziegler of Ziegler A List adds the following web resources:
— Catholic Encyclopedia: St. Basil the Great.
— The Rule of St. Basil.
— St. Gregory Nazianzen.
— Ven. John Henry Newman on SS. Basil and Gregory (from a work written in 1833, in his Anglican days).
— Pierre Subleyras, “Mass of St. Basil” (1743).