Some of the popular cloud storage services are Dropbox, Box, Google Drive, Microsoft Skydrive, iCloud, iDrive, OpenDrive, Mediafire and Backupandshare. There are of course many more in the market for you to choose from. You can check out from THIS website.
Recently a new cloud service has appeared to offer their services. I find the offer of 20Gb free storage very very exciting, far larger than other free services that offer from 2-7Gb. On top of this huge quota, during its launching promotion the company is also giving out free 5Gb for each successful referral made. Theoretically you can hit 100Gb or more free storage for your entire library of home photos, music and movies if 20 of your friends accept your invitations. Once you've registered you will be able to invite your own friends. For now if you are interested why not sign up at this secured website link.