Priesthood in the Hebrew Bible:
Ryan Bonfiglio, of Emory University, provides a historical overview of the origin, development, and influence of the priesthood in the Hebrew Bible.
Joseph Smith teachings on the Priesthood:
In this blog post, Joe Spencer provides a theological reading of chapter 8 of the Teachings of the Presidents of the Church: Joseph Smith manual (used as the LDS adult curriculum in 2008), which is drawn from several of Joseph Smith’s most important discourses on the priesthood. Definitely worth checking out!
Scott Woodward has nicely archived several of Joseph Smith’s discourses, including several that deal with the priesthood.
Relief Society Presidents’ discourses on Priesthood:
3.) Series of interviews on the Mormon Channel with Julie B. Beck (see especially this interview on “Our Spiritual Gifts and Connection to the Priesthood” – Episode 7 )