PhotoSite, the photo sharing site operated by Woodland Hills-based United Online, is targeting online backup of digital photos. PhotoSite said this morning that it has launched a new photo backup service called PhotoSite to allow members to securely store their digital photos online. The new service is priced by the number of photos stored, and costs from $1.99 to $2.99 per month. PhotoSite allows digital camera owners to upload and create web-based photo albums.