My old favourite xkcd recently ran a "map" (and I use the term loosely) charting the character interactions in a couple of great movies, including The Lord of the Rings, Star Wars, Jurassic Park, 12 Angry Men (amusingly), and Primer (even more amusingly). They're loving it over at StrangeMaps, and really, who can blame them?
For a more accurate, though far less amusing, plot of how Primer's brain-busting timeline worked, take a look at the diagram at Wikipedia... and then bust your brain some more at the page on Feynman diagrams.
(I'm a big, fat, nerd for Professor Feynman and his work. Anybody who can work on the Manhatten Project, diss string theorists, and still find time to frequent a hostess bar has to be alright.)