As it is Memorial Day, I always look to renew old bonds with friends, family and acquaintances who served.
For my Marine brothers and sisters (including Navy medical and religious personnel who served in Marine Corps Units) there is a free (well most features are free) MySpace-like networking site. Together We Served has a lot of interesting features, including: a section to add your units (already loaded in searchable directory); members directory that can be searched by name, MOS and other options; ribbon bar to list your ribbons, medals and rifle/pistol badges; unit patches directory that can be displayed on your profile, etc.:
http://marines.togetherweserved.com
In addition, I also recommend the free registry logbook for Marines and Sailors of all generations at the U.S. Navy Memorial:
http://www.lonesailor.org/navylog.php
Semper Fi