Through LiveMesh, SkyDrive users will soon be able to share photos and files, and they'll be able to determine the degree of access other users will have to those files. For example, access could be limited to the primary SkyDrive user, or it could be open to a select group of friends or the general online population.

While SkyDrive is moving toward a file-sharing and collaboration model, other online storage and backup service providers see a rich market in just allowing the average consumer to safeguard data. Among the leaders are Box.net and ProSoftnet Corp., which offers a service called iDrive.

And then there are the myriad resellers that use cloud-based storage from third parties. One such reseller is Jungle Disk LLC, which uses Amazon.com Inc.'s Simple Storage Service (S3).

Computer vendors such as Dell, Hewlett-Packard and Toshiba are also bundling online backup services with new PCs and laptops. Such services are available through providers such as Memeo Inc., which also offers its service via direct online sales.

Mozy is the oldest and among the most trusted of the consumer-based online storage services, which is probably one of the reasons why storage giant EMC acquired it. Mozy's service is straightforward -- the first 2GB of storage are free, and users pay $4.95 a month for unlimited online capacity. According to Dave Roberson, head of marketing at Mozy, the company has backed up 15 petabytes of data from customers.