Bread Crumbs

Informal

1. On Thinking for Oneself, by Arthur Schopenhauer
   
2. The Last Question, by Isaac Asimov 
3. Waking Life, movie by Richard Linklater
4. Meaning of Life, from Wikipedia
5. Philosophy, Physics, Mathematics - “Dangerous  Knowledge”, documentary by BBC
   
6. The Secret Life of Chaos, documentary by BBC
   
   

Formal

1. Predicativity, by Solomon Feferman
2. Self Reference, from Cut the Knot
3. The Paradox of Self-Amendment, by Peter Suber
4. Emergence, from Stanford Encyclopedia of Philosophy
   
5. Gödel, Escher, Bach: A Mental Space Odyssey, from MIT OpenCourseWare
6. Philosophy of Mathematics, from Stanford Encyclopedia of Philosophy

Works by Oliver Sacks and Douglas Hofstadter, to name a couple, are yet to be released in the Public Domain. Needless to say, most of them belong here too.