Primer is one heckuva cool movie. Two engineers who dabble with physics experiments in their garage make a mind-bending discovery after finding fungus growth on a weeble. Seriously. As many critics have pointed out, Primer is the most reality-grounded SciFi film since Kubrick's 2001: A Space Odyssey .
The coolest thing about Primer, however, is that is was made by a real software engineer named Shane Carruth. It was his first film, and his budget was a mere $7,000. It took Carruth nearly 2 years to edit the film, but the resulting story and cinematography (especially the excellent lighting) make him look like a seasoned pro. He discusses everything in detail (himself!) on the official Primer Movie message board.
I should note that the DVD I initially purchased had a defect that prevented the movie from playing past chapter 4. After I filed out the exchange form on amazon.com, I received a prompt reply and apology. They shipped me a brand new copy via 2-day air, and that disk plays without error. I'm very pleased with amazon's customer service.