I still am in touch with buddies that are still in The Army and I recieved an E-mail from my best friend (we've fought shoulder to shoulder) this weekend from Afgahanistan.
They could use a variety of things. This is something where you can help our men and women and possibily start a friendship (include a addressed envelope -- no need for any postage).
The best site to do this is
http://www.anysoldier.com/WhereToSend/
Click on anyone of the names on the right and you'll see just what they are asking for.
Also be sure to read what not to send (on home page).