if you use dropbox, you can use to share files that are too large to email, to have where you can get to them from any computer, or as a temporary back up. most of them have options to get up to 8 gig of free space. you can share folders or keep them all private. you can delete files from the shared folders, or the private folders, or otherwise use it the way you would a thumb/jump drive or external hard drive. you just have to have internet access to get to it.
i have used it a lot. one of my former students does photo restoration and while he was in town, he scanned a bunch of old photos for me, and has done work on them, dropped them into our shared folder, where i downloaded them to my computer. when we've finished working with them, we've deleted them. it is a good system, as long as you are cognizant that like all computer things, a separate back up is best.