On the lighter side, Letters of Note offers an interesting collection of private letters from various sources.
From the site: an attempt to gather and sort fascinating letters, postcards, telegrams, faxes, and memos. Scans/photos where possible. Updated daily by Shaun Usher
You'll find it at: http://www.lettersofnote.com/
One of my favorites is this template letter from the 9th century designed for a guest to send to his host the morning after getting too drunk at the party:
http://www.lettersofnote.com/2009/10/i-was-ready-to-sink-into-earth-with.html
Getting hideously drunk at a dinner party and embarrassing yourself is certainly nothing new. As far back as the 9th Century, the beautifully named 'Dunhuang Bureau of Etiquette' insisted that local officials use the following letter template (dated 856) when sending apologies to offended dinner hosts. The guilty party would copy the template text, enter the dinner host's name, sign the letter and then deliver with head bowed. The letter was discovered, alongside thousands of other documents, in a sealed cave library in western China.
Translated Transcript
Yesterday, having drunk too much, I was intoxicated as to pass all bounds; but none of the rude and coarse language I used was uttered in a conscious state. The next morning, after hearing others speak on the subject, I realised what had happened, whereupon I was overwhelmed with confusion and ready to sink into the earth with shame.