I forgot to mention this absolutely amazing radio segment about letter writing by Julie Shapiro (of Third Coast Int. Festival) for Radio 4. This is one of the most lovely stories I've heard about letter writing. I really enjoyed the way she wove in personal letters with other people's experiences, and even mixed in a bit of Lewis Carroll's Eight or Nine Words About Letter Writing. I especially liked Simon Roche's description of the tangibility of letters around the 20 min mark.
It's only available for online listening for 4 more days,
so go over and listen to it now!
(I'm not going to lie, I definitely teared-up near the end.)