Some things strike me about such letters. First, they were a critical means of communication for the Beat writers at the time. Phone calls would have been expensive and, besides, Jack et al. were often living in situations where they had no easy access to a phone. Yes, there were phone booths in the 1950s, but one or the other party had to be at a particular phone at a particular time in order to make a connection. Plus it cost money, something they often didn't have. Second, the letters reflect the reality that these were friends communicating not just across distance but across time as well. In his 1958 reply to Jack's1957 letter (8 months later!), Holmes starts the letter saying,
Again I find myself in the position of not knowing where the hell you are, and having lost or mislaid all addresses but for some that must certainly be out of date, and so having to rely on Viking to forward this, despite the fact that Grove Press might have a better idea where you actually are.
Third, these are incredible letters in terms of content. They go on for pages, touching on everything from mundane current events to mystical ponderings and sometimes including poetry. Accordingly, they provide important historical information as well as insights into the personas of the Beat writers.
I've written about this before (for example, The Selected Letters of Allen Ginsberg and Gary Snyder), but in case you missed my earlier admonitions, I wanted to take an opportunity to commend such reading as part of your Beat education. If you're a Kerouac fan, I have no doubt that you would thoroughly enjoy reading the letters of the Beat writers.
Finally, and fourthly, the last thing to strike me was the dearth of letter writing occurring today. There is something special about writing a letter to a friend, versus sending an e-mail. E-mail seems so ephemeral, whereas letter-writing has an aspect (imaginary, of course) of permanence. Writing a letter to a friend is a commitment. Zapping off an e-mail doesn't have the same gravitas.
I correspond routinely with two friends, one in New York State and one in California. I look forward to their letters and they mine (so they tell me), and it just seems like we say things in letters that just don't get said in other communication mediums.
Your Kerouaction for this day is to take pen and paper in hand and write a letter to a friend. I bet something pretty wonderful will happen as a result.