In saving these files I make sure to password protect them. Since the method to password protect a file differs by program used and version of that program you need to go to the help section to determine how to password protect the file. I then email the file to myself. What I am doing here is adding an extra layer of security to information that if it fell into the wrong hands would make me more susceptible to identity theft. One would need to know both my email password as well as the password I am using to protect the respective files that contain this sensitive data. I would suggest making the passwords for your email and files different.
One does not have to limit to just credit cards, passport and drivers license. Scanning current drug prescriptions you are using and saving them to a word type file is another good idea where you have a copy of the prescription. This way if you were to lose the prescription drugs you had packed, you should have an easier time refilling it. You can also put the numbers of your travelers checks in a file as well. I also keep my phonebook in my Google contacts list so should I need a number I can get it wherever I have an internet connection which would include my smartphone.
Doing all of these is not a magic bullet should you have a loss. It will however make it easier to travel and in the case of a passport get a replacement more easily in the event of losing any important documents. I would also suggest that you avoid using an unsecured public wireless network to obtain any of this. If you have a smartphone, you can likely access this information using it. That said another way to store your files is if you are using a syncing program likeDropbox or Sugarsync. You can log onto the one you are using to access the information in question. I will suggest here that you do not save this information on the hard drive of any computers you may be travelling with. Better that it is in the cloud where the data and you are not in the same place. Also should your computer get lost or stolen, you can still access it from another computer. If anyone is interested in opening a Dropbox account let me know before setting up your account. I will send you an invite to join Dropbox and both of us will get an extra 250mb of free storage. A win/win for both of us. Note: as I mentioned in my blog last week, you cannot upload or save a password protected file in Google Docs.
Hopefully you will never need to access these files in an emergency. However, having them in an emergency can make your life easier when it occurs.