Landed at a podunk airport in WV after shooting an approach to minimums in a non-radar environment with poor radio coverage. Since I didn't get a phone number from ATC, I made the mistake of thinking that the fastest way to cancel my IFR would be by calling Lock-Mart. Called their dedicated IFR clearance number (888-766-8267), and waited on hold for 10 minutes. Meanwhile a guy drives up in a truck to tell me that ATC called him asking if I was on the ground, and he told him I was, so the flight plan got cancelled. That's when flight service finally answered, "Lockheed Martin Flight Service, can I help you?". "Sorry, no. I got what I needed while I was on hold." Not exactly efficient.