Countdowns - Once dates were confirmed for the R&Rs, we created these. It helped to see how much longer we had to go. We did one vacation themed, holiday themed, and candy themed (pre-counted M&Ms in 2 jars with the kids names on it, they each got 1 a day until he came home)
Skype calls - We scheduled 2 separate calls, one for the kids to talk with their dad (it happened usually in the morning before they headed to school) then he would call me in the afternoon and we'd have our time to discuss house stuff, the kids, etc. This has probably been the sanity saver for all of us as we still felt very connected. The kids have never had their dad gone for more than a quick trip for training or work (usually no more than 2 nights).
Reading in person - To help me with the kids school work, he downloaded a book to his iPad for reading with the kids over the computer. They would share the reading with each reading a paragraph. He downloaded a book for each of the boys, so they had their own time with him. This really worked great as they felt that daddy was involved in their school work.
As the mail wasn't reliable after the holidays (especially since my husband was not at the Embassy, but at an Annex) instead of sending things through the mail, we sent e-cards, and emails with pictures of things we wanted to send him. We also sent lots of pictures of places/things we saw/did.
Because of events of this year that we wanted to attend together (a close friend's wedding, our 15th anniversary) we decided to do a long stretch from the 1st R&R to the 2nd. That was the most stressful for both of us as he left right after Christmas and didn't come home again until May. During that time thankfully it was basketball season and scouts was well underway. I had begun to volunteer more at the school, which was very helpful for keeping me out of the house and during the times when calls would not be coming. Plus volunteering is so flexible! It was just hard to have to go such a long stretch, that we would not recommend it to others, unless absolutely unavoidable. Looking back it doesn't seem so bad now, but I remember during the time that I was thankful for volunteering, the kids busy schedules, and having friends around. Granted not many are familiar with the FS life here in small town PA, and sometimes, that was exactly what I needed.
Thanks to Jennifer! Excellent tips!