Until this April, the answer was Dropbox, which provided 2GB of free storage, ways to share folders, and a good automatic sync between your various devices. If you want a short intro to Dropbox, you can find it here.
Google Drive, which came out this past April, can serve the same function
as Dropbox in terms of online storage.
Should you switch? If you are using Google software for other things, e.g. Gmail, it is
easiest to use Google Drive for storage. If you are not using Google for
other stuff, staying with Dropbox or switching to Google Drive may be a
tossup, depending on your needs. If you want to read more on the trade-offs between these two options, Lifehacker has a good article. If you want to read more on many more online storage options, Verge has a good article.
