I know I'm not the only one interested in getting copies of some of letters from the first presidency. Some of these are available at LDS.org, but they are usually tucked away in obscure places.
To date, the only place to get a complete list of letters is at apps.lds.org, and only stake presidents have complete access to the site:
A list of First Presidency Statements that leaders have been instructed to read over the pulpit can be found at the Church News site. It goes back as far as 1999:
Here is a short list of letters relating to youth, but only some are available to read online:
Here's an old letter about how Bishops should be involved in ward missionary work:
Here's a post that describes changes in the FP letter about not harassing Church headquarters with questions that can be answered at a local level. It's interesting to see how the wording has changed:
I understand that the Church Handbook of Instructions has a list of letters that are still valid. See: