What are some resources you have used to try to find old wartime buddies?

My personal website includes a weblog with a section devoted to my experiences in Vietnam during my tour of duty. During the 20+ years since I created it, I have received comments and communications from other veterans searching for old wartime buddies. One arrived recently from the child of a Vietnam Veteran asking for help finding anyone who served with her father in the unit and during the time period she mentioned.

It's difficult. Few of us deployed with our units as happened during earlier wars. Very few of us served in units that were formed from persons who were drafted/enlisted from the same neighborhoods. And when we returned, most of us shed any vestige of our military service to avoid the rancor of the antiwar crowd.

However, with age, many of us begin to think back to those times. We'll never again be the men we were then, will we?

In helping them, I have discovered a couple of resources and am now considering writing an article, a guide to resources for locating prior service personnel. I would appreciate your help in growing my list of resources.

Please share.