Sailor Moon, back when it showed on USA at 4 in the morning. We didn't have cable, so I had to settle for seeing it once in a hotel room and later bought some tapes.
I don't know if it's common, but I learned about anime through the internet. So before I had even seen my first episode of Sailor Moon, I had read all I could about the characters and saved tons of pictures. I can still remember shit from the end of the manga and I never even read it. Kinda a sad life for a 3rd grader with dial up. Thank god we have high speed internet and torrents now.