He asked me to marry him before he left but I never gave him an answer and now that he's gone I decided I want to marry him. He's over in korea and I am in the us. Is there any way we can get married with him there and me here?

Over the phone with a minister or pastor or something. Whatever your faith.

I found this link that might be of interest to you.

Google Answers: "Getting Married over the Internet" (http://local.google.com/answers/threadview?id=245820)

He asked me to marry him before he left but i never gave him an answer and now that he's gone i decided i want to marry him. he's over in korea and i am in the us. is there any way we can get married with him there and me here?
Wait intill he's back

Marriage by proxy is done in places. See the following link about that.
Marriage By Proxy (http://www.marriagebyproxy.com/)
Proxy Marriage (http://marriage.about.com/cs/legalities/a/proxymarriage.htm)

While I did not check out all the links given you, it is correct some states will allow you to get married by various means. I will say this, his time in Korea should be fairly short tour of duty, and he will get various leave times. If there was , and it appears there was a reason you did not say yes within 1 minute of being asked but had to think about it, perhaps you need to wait till he gets home and be 100 percent sure.