This used to exist as 'penpals' and I am sure that the digital medium is no less - probably more - fun.
There will be a list of people divided by age, gender, interests, etc.
Write to someone and see what they have to say about - well, anything you like.
Sending pictures, stories, favourite links with another person
I imagine email might be the main medium but there is something very nice about getting a letter or postcard from a foreign country.

Perhaps this section could be included under 'chat' but I built the menu first and have been working out wha it all might mean as I go along. One of the main reasons for this site is to get people in touch with other people.
Start a new friendship with one person.
Or, it could be a small group of people who find that they have a common interest.

What else can you think of here ...?