I just wanted to say thank you for your brother's service and know that all the troops are in our daily prayers for a safe return. My son just got home from Iraq in September and will likely go back before long. I know how anxious it is for your whole family.
A lot of the other suggestions are great ones. Some of the other things that I sent my son were:
Axe hygiene products (although my son said that Infantry soldiers don't worry about hygiene - I can attest to that by the way they smelled when they arrived home!)
Batteries
Gum
Water pistols
CDs and Movies (write his name on them in Sharpie marker – they get lost and stolen pretty quickly)
Books/Magazines/Puzzle books (Sudoku, Crosswords, etc.)
A variety of packaged food (trail mix, ramen noodles, cookies like Oreos, Little Debbies, granola, microwave meals, Pringles, pudding, popcorn, protein bars, ravioli, nuts, snack bars, tuna, hot cocoa and coffee if he likes it) Make sure you put plastics spoons and forks if it's not finger food
Foot Powder
Warm socks
Alcohol (!! I sent him some vodka in a water bottle)
Homebaked cookies/brownies (Seal them in Ziploc bags and pack them tightly. If you shake the box and anything moves it will be in crumbs when it gets there)
Letters/Pictures
My best suggestion is to send fun things, letters and pictures. The military has set up a decent quality of life for the soldiers over there and most of the time they have access to a PX to purchase day to day stuff that they need. Sean even purchased a laptop over there so the PX is a lot like a Meijer/Walmart. In the outlying FOBs (Forward Operating Base), they still usually have a Shoppette with the essentials. Send things that you know he likes or things that will brighten his day/holidays. Have the kids make cards. Our younger sons' school all did cards and sent hundreds of them. He can share them with his buddies and they are so fun to read what kids' perception of the military and war is. Lots of misspelled words, letters written backward, etc.
Package everything very tightly. The post office has a box that is a flat rate ($8-$9) no matter how heavy it is and we got a bunch of those and packed them full. Also, keep in mind that you will have to fill out a customs form with a list of everything in the box. It is better to send smaller packages than a big one. They are easier to transport and more likely to get there sooner. If he is outside a major FOB, mail goes on supply trucks as there is room. Use lots and lots of packing tape.