“Disenfranchised Over There” in The Weekly Standard discusses the important issue of how to facilitate voting by military personnel based outside the United States.  The Military Voting Protection Act appears to address some of the issues mentioned in the article, and the article considers an additional solution:

Imagine a system where Congress and the states coordinated an effort to set up early voting sites at or near military installations all over the world. Once a voter provides proper identification that matches his or her name on the voter registration lists each state is required to maintain by the Help America Vote Act of 2002, an electronically uploaded ballot provided by that state could be printed out for the soldier. The ballots completed at each overseas early voting site could then be sent back to the appropriate election officials in the United States through express mail.