A lot of mine are centered on technology (Facetime, Skype, etc.) However, this can be a double edged sword. If my wife and I talk everyday, we soon run out of things to talk about after the obligatory "what did you do today, how are the kids, etc." The last time we were seperated, we would still facetime daily, but we wrote an ongoing letter to each other that had our thoughts during the quiet times. This became a really fun gift to each other when we reunited. Now we have those journals that we can look through and remind ourselves of different feelings and events that help to strengthen our relationship even now, years later.
For my daughter, when I am home, it's my job to tuck her in and read her a bedtime story. I was very lucky that through skype and a coincidental schedule, I could continue that while we were seperated. That definitely helpe keep us close while we were so far apart.