The key to understanding Ignatius, the order he founded, and themes that inspire Jesuits in their work is a small book that Ignatius put together during his "pilgrim years," when he was slowly learning to understand himself and the life to which God was calling him. He called the book Spiritual Exercises. A variety of resources that will introduce you to Ignatian spirituality are available online.
For another approach to Ignatian spirituality, one adapted to undergraduates, look at the chapter "Spirituality and Life's Journey," in What Are We? An Introduction to Boston College and Its Jesuit Tradition.
Spirituality, and especially Ignatian spirituality, is a vast topic. There are a number of more popular presentations of Ignatian spirituality that do not dumb down the issues and are worth reading. Among these are: Listening to the Music of the Spirit: The Art of Discernment, by David Lonsdale, S. J. (Ave Maria Press, Notre Dame (Indiana), 1992) and The Way of Ignatius Loyola, Contemporary Approaches to the Spiritual Exercises, edited by Philip Sheldrake, S.J. (Institute of Jesuit Sources, St. Louis, 1991). An unusual but fresh approach interprets Ignatian spirituality as a theory of communication, Directions for Communication, by Willi Lambert (Crossroad Publishing Company, 2000).
Ignatian spirituality offers foundational principles that are especially useful for thinking about human development and education. In an article in America, Timothy Muldoon, '92 offers Ignatian Spirituality as a valuable resource for the young adults of "Generation X" and "Y" who are currently making their way through higher education ("Why Young Adults Need Ignatian Spirituality," 26 Feb., 2001) .
A number of web sites offer resources for exploring Ignatian spirituality:
Boston College's Center for Ignatian Spirituality
Sacred Space is a website run by the Irish Jesuits. They invite you to make a "sacred space" in your day and spend ten minutes praying here and now, as you sit at your computer, with the aid of passages and reflections they provide.
Creighton University's Collaborative Ministry Office offers daily reflections on Scriptural passages written by members of the Creighton community; weekly reflections on the liturgical reading from the upcoming Sunday; and the opportunity to make a 34-week version of the Spiritual Exercises on-line.
The U.S. Jesuit Conference web site offers a variety of largely informational resources about Ignatian spirituality at their web site: http://www.jesuit.org/