Dialog
Unreal 2 has a system for creating dialog between actors. It seems to be quite a simple thing to set up, and there's a currently undocumented conversation editor that can be used. Conversation files are stored in text files on disk, and are read in when the relevant level is run.
scumble: I put this up here because I'll probably have my own tutorial for it soon, and maybe some technical info. I was just particulary interested in this part of the U2 code.