You might be able to run the game from a usb key drive and carry that around. I am not sure how difficult it might be but it would be worth a try.
You don't have to run the whole game on the stick. Just put a symlink to a file on your usb-stick rather than the file directly in your game folder. Works great on unix. I do the same with my .gnupg because I don't want to leave my private key on other machines in the university or similar.
There is nothing like a working symlink on Windows XP or earlier (.lnk are not the same), but I heard that something like this is possible in Vista.
PS:
Gmail is not a solution, it is just an example for one solution: email it to some webmailprovider every time you played the game. Which is a bit of a hazzle, but it works. Another option would be an ftp server because you can build an automatic script that does the downloading and uploading with a simple keystroke or similar.
PPS:
I am no fan of Gmail..