"Open when..." envelopes! These are perfect for military deployments or long distance relationships, etc. I grabbed 10 envelopes and put hand written letters in each of them, some with little treats. I also made an 11th envelope for just pictures!
Daddy's Deployment Wall is an interactive way for the kids to track deployment progress. A bubblewrap countdown calendar, world map with ship cutouts to track Daddy, candy jars with bedtime gummy bears hugs from Daddy, mailboxes and clocks for Daddy's Time and Our Time.