I'm about ready to return home and this deployment has been much more comfortable than past ones. However, even on "larger" FOBs that have a PX, items are quite scarce and picked off immediately by the PX-Rats and most coalition forces. Toiletries are always nice and we even package up unused items for dropping off at smaller sites or local nationals (kids, widows, etc.).
My personal favorites:
Instant Coffee (Singles or Starbucks VIA)
Drink mixes (such as Emergen-C, hot cider, hot cocoa, etc.)
Nuts (Pistachios, almonds, mixed, etc.)
Dried fruit/trail mix
Little fruit candy snacks (just received a box...love those little things and most are loaded with vitamin-C)
Engery/Granola bars (Clif, Granola, etc.)
Gun magazines (my son picks them out for me)
Commercial internet access is pretty good in some locations and my best deployment gift this time around was a Kindle. I downloaded about 100+ books and received a few gift cards; lot's a of great zombie fiction to fill what little time I get.
Lastly, I'll add that a personal note/letter is nice and I've returned several.