The problem of suffering is one of the biggest intellectual challenges to the concept of a benign, omnipotent and omniscient god. As such, lots of people have written about it, including Aristotle, Augustine, Aquinas, and various biblical Authors. Those are the ones beginning with A, anyway. A truly funky site that I have found is the UCCF (University Colleges Christian Fellowhip) site www.uccf.org.uk - have a look round the rest of the site as well. It also appears to contain humour which is unusual. (It is unusual that the site contains humour that is. Mind you the humour itself is quite unusual if you know what I mean. I'm sorry I'm wittering again.)
Also look out for The Problem of Pain by CS Lewis - a most excellent read. You can even order it off the internet (at www.amazon.co.uk if you haven't been conscious for the last few months).
If you're interested in drugs (and as a medical student, you should be), try out Patrick Dixon's Site at www.globalchange.com