For the emotional problem of evil – pain, death & suffering, see this post.
The best apologetic (defense) on this topic that I have yet come across by William Lane Craig (from Reasonable Faith). It is often not clear that the problem of evil (why a good & all-powerful God would allow evil to exist) contains some implicit assumptions. This discussion brings those assumptions into the open & illustrates the flaws in them. It also shows why, with the Christian world-view the existence of evil in the world is expected (to some degree).
Part 1:
Part 2:
Part 3:
You can also download the MP3s here: Part 1, Part 2 & Part 3.