We have many web cloud service here, most basic free accounts are only about 2 - 5GBs, if you want to more space you have to pay. Now, a new website - BeeCloud offers 512GB web cloud space to everyone for free. Really? Yes, this is basic free account, only for backup your files, it isn't for sharing. BeeCloud is a reseller of Livedrive, so it uses Livedrive servers to store your file. Livedrive is a commercial web cloud service company, only offers web space to commercial users. If you direct go to Livedrive you can't find free account.
For backup your files, you have download and install a client, choose a folder you want to backup in your computer. It'll backup this folder in to web cloud space automatically. I did try, it works. I only worry about how long BeeCloud keep this free service.
Update (03/01/2012): This website is no long offer this web cloud backup service, it ends reselling with Liveddrive. I always worry about this kind of reselling site, you never know how long it keep your files.