I mentioned this on Quodlibeta a while ago, but I thought some of you folk might appreciate it as well: Plantinga's trilogy on warrant is available to read online.
Warrant: The Current Debate
Warrant and Proper Function
Warranted Christian Belief
The first two are series of Gifford Lectures (which I wrote about here), and the last one is hosted at the Christian Classics Ethereal Library. Enjoy.