With the space that Yahoo! offers today, it is a great place to store your files, at least temporarily. It would always be better to use a full fledged file backup service. However, on the plus point here you can create unlimited email address. While it would be cumbersome to keep saving drafts, you can use a simple tool that would automate this for you.
Yahoomail Folder is one such utility that uses your Yahoo! Mail account as a virtual storage medium.
You can copy files to your Yahoo! Mail account by using drag and drop or the context menu. If you add files to your account, this tool generates an email and sends it to your account.