From one of those 'question and answer' type columns in the Capital Times:

FYI: What songs did Nero fiddle while Rome burned?

- Classics lover

• One possibility is "The Wreck of the Old XCVII" (later recorded in MCMXXVII by Vernon Dalhart to become the first record to sell a million).

Seriously, Mailbits.com says Emperor Nero Claudius Caesar couldn't have fiddled while Rome burned in A.D. 64 because the violin wasn't invented until the 1500s. He is reported by the historian Suetonius though to have watched Rome burn while he sang a song about the destruction of Troy.

"The first reference to Nero's fiddling appeared in the mid 1600s. The word 'fiddle' seems to have been used to mean 'engaging in frivolous activity,' not 'playing a violin.' When he was through singing, Nero blamed the fire on the Christians and began the first Roman persecution. Others, pointing to Nero's desire to rebuild Rome on a grand scale, note that the fire was a very convenient way for him to carry out his plans and suggest that he may have caused the fire himself."

The Concise Columbia Encyclopedia notes that among Nero's modest last words were, "What an artist the world is losing in me."

Tony Peyser, a satirist and cartoonist, compares A.D. 64 with the U.S. Capitol evacuation in D.C. 2005: Now, at last, The issue's settled: Nero fiddled, Bush, he pedaled.

I always thought it was just a gloss on using the lyre as one recited lyric poetry. In any event, Cassius Dio 62.17 is a bit more specific (text via Lacus Curtius):

While the whole population was in this state of mind and many, crazed by the disaster, were leaping into the very flames, Nero ascended to the roof of the palace, from which there was the best general view of the greater part of the conflagration, and assuming the lyre-player's garb, he sang the "Capture of Troy," as he styled the song himself, though to the enemies of the spectators it was the Capture of Rome.

Suetonius (Nero 38) concurs:

Viewing the conflagration from the tower of Maecenas and exulting, as he said, in "the beauty of the flames," he sang the whole of the "Sack of Ilium," in his regular stage costume.