I started listening to the APs back in September I think. I'd listed to the Penny Arcade DnD podcast and thought they were great. That's what got me into DnD. Then on the PA forums I found a couple PbP of Call of Cthulhu that were interesting enough to read. They were doing The Haunting, which I didn't realize at the time was a published adventure. I remembered at that point that I liked listening to AP podcasts, so I googled The Haunting AP and found RPPR through that.
Yup, my first RPPR AP was Aaron's epic The Haunting game. It was so hilarious (Scientologist brothers, Pancake Jamboree, Cody) that I had to listen to more. I devoured all the CoC shortly thereafter, then New World, Eclipse Phase, and now I'm on New Arcadia. When I get caught up on those I have no idea what I'll do in the time between Ross postings.