My nephew was in Afghanistan for a while, and I sent him quite a few packages. I did send a couple of computer games recommended by my son (since I am clueless when it comes to that stuff) One was called "Orange Box" and as I recall it contained a couple of different games that were pretty popular. (This particular thing may be outdated now. My son suggested it since it came out after my nephew was sent over, so we knew it was something he wouldn't already have).
I also picked up several of the cheap DVDs from Target and Walmart - the $4.99 bins and such.
I would send small, individual-sized packets of baby wipes, or "wet ones," as I've heard they like those, and the smaller packets are easier to carry around.
Foot powder, deodorant, lip balms, snacks, snacks, snacks - lots of those small plastic containers of things like salsa, or queso dips, or ranch dips. You can get them in packs of 4.
Apparently, another thing they tend to like is the flavorings for water - I sent over a couple of bottles of that "MIO" stuff, or the little powder packets. Apparently, they have plenty of bottled water, but tend to get sick of it (understandably) so the flavorings are a welcome change of pace.