Wil Wheaton (most known as Wesley Crusher in Star Trek: TNG) has posted on his blog a request for fellow nerds to donate their Gmail invites to troops who are serving overseas. Actually makes a lot of sense. The 1 GB of space that Gmail offers is perfect for photos, movies, sound files, and lots of e-mails from family and friends of the soldiers.
Right now it looks like the best way to donate your invites is to go onto Gmail Swap, although it appears there are people who are trying to organize a dedicated web site for this task. Good luck to them and donate your invites!