Here's a couple on US... I'm sure there have to be others.

New Year's Eve 2001 / New Year's Day 2002
Went out to SFO to see the Hokie's play a bowl game. The 6:30A from BLF-PIT had 3 pax on the B1900. On the return, it was a 4PM flight on New Year's Day. Waiting in (now deserted) terminal F in PIT... at 3:45 some pilot, who was commuting home back to BKW says "Who's going to BKW/BLF?". I say me. He says "Let's Go.". Ended up being him and me on the B1900. He went back and crashed on the 3 across in the back. I enjoyed the beautiful flight on a cool clear day with the crew door open.

Sometime in summer '96. PIT-CRW. Went out on last flight on a Sunday night in FC on a 737. By the time we got to CRW, airport was fogged in. Circled and retried 3 or 4 times before we went back to PIT. Hung around the gate (by this time it's like 10PM), had already been rebooked on the first flight on Mon (like 9AM) and heard they had to move the plane anyway so they didn't have to cancel the 6:50A from CRW-PIT. So, I ended up getting booked on a non-scheduled flight at like 5:30A, as did about 5 other of us. I went to a closeby hotel for 6 hours, came back at 5 and got on. We all sat in FC, had 3 FA's to ourselves for the 25 min flight back. I was able to get off the plane, get to my car, make the 90 minute drive down the WV Turnpike home and still be back before 8 AM.

When CCAir was still flying out of BLF/BKW, I had several BKW-PIT B1900 flights with maybe 3 pax total. I don't recall many small loads when flying out of RDU or ROA... except for either Christmas or New Year's Eve in '87 when there were maybe 15 of us on a DC-9 to PIT.

I do remember one more... in '88, a late night flight from SYR-BUF on a F-28... maybe 5 of us on the flight at about 10PM. Those were the days... and that's right before the PI merger, too, as that flight was on PI.