Today is the International Day of Non-Violence. I don't expect you'll find too many Hallmark cards to celebrate this particular day, but it's a good time to stop for a few minutes and reflect on the tradition of Christian pacifism. (Disclaimer: I'm not a pacifist, but I find a lot of the arguments for nonviolence compelling.)
My own introduction to Christian pacifism came in the form of John Howard Yoder's book The Politics of Jesus. Until I read Yoder, I imagined pacifism as the sort of thing only fringe political groups or the politically naive could embrace; Yoder's book demonstrated that it was a coherent philosophy with a strong claim to Biblical support. I strongly recommend Yoder's book if you've not read it; I did find a lengthy summary of The Politics of Jesus online if you want an abbreviated version. Elsewhere online, Stanley Hauerwas has written an excellent piece that draws on Yoder and argues that pacifism should be considered and debated much more seriously by the Christian church.
If you're up for yet more reading, have a look at this extremely impressive collection of Mennonite-Anabaptist resources about pacifism. The theological and Biblical studies are a good place to start and address a lot of the basic arguments for and against Christian pacifism.
A few more links, if you'll bear with me: Kim Fabricius has written a fascinating account of a journey to Christian pacifism at the Faith and Theology blog. The post cites a lot of authors and books worth investigating. It also mentions the famous 20th century pacifist Dietrich Bonhoeffer, who believed in nonviolence but who ultimately participated in a plot to kill Hitler during World War 2. Ronald Osborn writes an interesting piece about Bonhoeffer's moral crisis and how he understood his decision to take violent action against evil [PDF].
That's a lot of reading, but I hope you'll take a few minutes to explore around a bit. Whatever you think of Christian pacifism, it makes serious claims about the Bible's teachings, and every Christian should take some time to consider them.