If anyone's interested, I just uploaded an extensive list of spawnable entities in Kingpin (I don't think I missed any, but I might be wrong) plus what I believe to be all key/names pairs available (there got to be more, even with the source code it's hard to keep track of everything). I also included a few info regarding single player stuff such as cast names, ai_flags, map names and weird hacks. It's right there (work in progress, not really practical or ordered for now, there will be a downloadable version when the stuff looks clean enough)
EDIT: Updated link. Silly me.