Clonezilla is a partition or disk cloning tool similar to Symantec Ghost. It saves and restores only blocks in use on the hard drive if the file system is supported. For unsupported file systems, dd is used instead. It has been used to clone a 5 GB system to 40 clients in about 10 minutes.
rsync is a replacement for rcp (and scp) that has many more features. It uses the "rsync algorithm" which provides a very fast method for remote files into sync. It does this by sending just the differences in the files across the link, without requiring that both sets of files are present at one of the ends of the link beforehand.
G4L is a hard disk and partition imaging and cloning tool. The created images are optionally compressed, and they can be stored on a local hard drive or transferred to an anonymous FTP server. A drive can be cloned using the "Click'n'Clone" function. G4L supports file splitting if the local filesystem does not support writing files larger than 2GB. The included kernel supports ATA, serial-ATA, and SCSI drives. Common network cards are supported. It is packaged as a bootable CD image with an ncurses GUI for easy use.
HTTrack is an easy-to-use offline browser utility. It allows you to download a Web site from the Internet to a local directory, building recursively all directories, getting HTML, images, and other files from the server to your computer. HTTrack arranges the original site's relative link-structure. Simply open a page of the mirrored Web site in your browser, and you can browse the site from link to link, as if you were viewing it online. HTTrack can also update an existing mirrored site, and resume interrupted downloads. WebHTTrack is a Web-based GUI for HTTrack.
Super Flexible File Synchronizer lets you back up your data and synchronize PCs, Macs, servers, notebooks, and online storage space. You can set up as many different jobs as you need and run them manually or by using the scheduler. The software works with local hard drives and any other mounted volumes. In addition, it comes with support for FTP, SSH, HTTP, WebDAV, Amazon S3, and Google Docs. You can use Zip compression and data encryption. There are powerful synchronization modes, including Standard Copying, Exact Mirror, and SmartTracking.
Lsyncd watches a local directory tree's event monitor interface (inotify). It aggregates and combines events for a few seconds and then spawns one (or more) process(es) to synchronize the changes. By default, this synchronization is done with rsync. Lsyncd is thus a lightweight live mirror solution that is comparatively easy to install. It does not require new filesystems or block devices and does not hamper local filesystem performance.