I don't know if these have been mentioned...
Julius Africanus, writing around 221 AD, found a reference in the writings of Thallus, who wrote a history of the Eastern Mediterranean around 52 AD, which dealt with the darkness that covered the land during Jesus's crucifixion:
"Thallus, in the third book of his histories, explains away the darkness as an eclipse of the sun--unreasonably, as it seems to me." [A solar eclipse could not take place during a full moon, as was the case during Passover season.]
----------
Pliny the Younger, Roman governor of Bithynia in Asia Minor around 112 AD:
"[The Christians] were in the habit of meeting on a certain fixed day before it was light, when they sang in alternate verses a hymn to Christ, as to a god, and bound themselves by a solemn oath, not to any wicked deeds, but never to commit any fraud, theft or adultery, never to falsify their word, nor deny a trust when they should be called upon to deliver it up; after which it was their custom to separate, and then reassemble to partake of food--but food of an ordinary and innocent kind."
----------------
Lucian, a second century Greek satirist:
"The Christians, you know, worship a man to this day--the distinguished personage who introduced their novel rites, and was crucified on that account. ... You see, these misguided creatures start with the general conviction that they are immortal for all time, which explains the contempt of death and voluntary self-devotion which are so common among them; and then it was impressed on them by their original lawgiver that they are all brothers, from the moment that they are converted, and deny the gods of Greece, and worship the crucified sage, and live after his laws. All this they take quite on faith, with the result that they despise all worldly goods alike, regarding them merely as common property." Lucian also reported that the Christians had "sacred writings" which were frequently read. When something affected them, "they spare no trouble, no expense."
-------------
Mara Bar-Serapion, of Syria, writing between 70 and 200 AD from prison to motivate his son to emulate wise teachers of the past:
"What advantage did the Athenians gain from putting Socrates to death? Famine and plague came upon them as a judgment for their crime. What advantage did the men of Samos gain from burying Pythagoras? In a moment their land was covered with sand. What advantage did the Jews gain from executing their wise king? It was just after that that their kingdom was abolished. God justly avenged these three wise men: the Athenians died of hunger; the Samians were overwhelmed by the sea; the Jews, ruined and driven from their land, live in complete dispersion. But Socrates did not die for good; he lived on in the teaching of Plato. Pythagoras did not die for good; he lived on in the statue of Hera. Nor did the wise king die for good; he lived on in the teaching which he had given."
Excerpted from: http://www.westarkchurchofchrist.org/library/extrabiblical.htm