The things my husband asked for once he got out there were a crate mattress (I bought a queen size so that he could cut it in half and have double the cushion), sheets, contact lens cleaner, and black socks.
It reaLLlly will depend ... like if your husband wears contacts sending some lens cleaner is good because they dont sell it over there (at least not where my husband is stationed at), because technically they shouldn't be wearing them over there. I also send my husband his toilet paper ... because he is VERY picky about what kind he likes to use, so I figure a little thing like that can mean a lot. But little stuff he likes that you know, maybe his favorite cookies or candy, etc. One thing too, is I always try to send enough stuff so that he can share with his fellow Marines ... you wouldn't believe how many of them don't get care packages and they appreciate it so much.
Anyway, I went through the posts here and found some really great ideas. So that may help you out too. Oh-yeah, I dont know about your husband but mine hates the black socks they get at the clothing store because apparently the half of it shrinks and half of it doesn't. So, my family also sends him black "Wilson" socks from K-mart or Walmart. Anyway, hope this helps.