(this HTML version)
That HTML version was my first version of the Principia as well. I printed the whole thing out and carried it with me everywhere. I was fifteen or sixteen, and had recently cast aside Christianity in favor of atheism, then atheism in favor of Taoism (they're not exclusive, but meh), then finally Taoism in favor of Discord. Recently I cast Discord away in favor of Discord, then cast
that away in favor of Discord.
When I was 17 I bought Illuminatus! totally randomly. (I think it was on sale)
When I found out it was about Discordia, I went

other books / authors I sometimes find relevant to my personal version of Discordja
-Cosmos by Carl Sagan - underscores the universe's beauty
-Prime Chaos by Phil Hine - underscores the power and mutability of beliefs
-parts of Metamagical Themas by Douglas Hofstadter - made me fascinated by pattern recognition and creative process
-some Carlos Castaneda
-Edith Hamilton's retelling of Greek Mythology - underscores the harsh, impersonal arbitrariness of the universe
-The Hero with a Thousand Faces (Campbell)
-Fight Club
-Parts of the Apocrypha Discordia
I think the movies Waking Life and I Heart Huckabees also influenced my beliefs a bit.