I flew without passport or ID once, when my passport was stolen in Germany and I had to return to my country of residence, Switzerland at the time. I am a Danish citizen and I called the embassy who told me they could only get me to Denmark through the partly state owned airline Scandinavian Airlines, but I managed to talk to the the relevant people at the airport and I even managed to get a VAT refund from a jacket I bought in the airport and eventually got back to Switzerland on my scheduled flight.

Yes, my family and myself had our passports stolen in Tenerife (now known as Tenergrief in my family, wasn't the best of holidays) and we flew back to the UK on a police report (which was in Spanish).

The UK customs officer said we shouldn't have really flown back on that, but he let us in regardless. Not even an interview in a room.

It's sort of irrelevant now in this particular case, because Snowden is traveling on refugee documents from Ecuador.