Iperius Backup Free is an interesting and very configurable free backup tool.
The program offers a clean and simple interface. You don't have to explore a host of nested menus to figure out exactly what it can do: everything you need is accessible via few buttons.
There are still plenty of options, though. When creating a backup, for instance, you can include multiple source files and folders. A powerful scheduler allows you to run particular jobs on certain days of the week or month, at regular intervals (every 12 hours, say), and even tricky timescales like "the third Tuesday of the month". Iperius Backup Free can also send emails when the backup is complete to report what's happened, and you can have the program launch particular applications before and after your backup job runs.
This is the free version, of course, and so it has some restrictions. The most significant being that the program can't copy open or locked files, so if, say, you run a backup while Outlook is open, then your PST file (Outlook's main data store) won't be included. It also doesn't include a Disaster Recovery drive image, so can't be used to restore a system which won't boot any more. Check the Iperius comparison page for more.
If you just need a straightforward file backup tool, though, Iperius Backup Free could be sufficient: it's small, easy to use and very configurable.
Note that Iperius Backup is now compatible with Windows 8/8.1/10 only.
Version 5.1.1 improvements (full changelog) include:
Backup on Google Drive and OneDrive: synchronization speed has been improved
ESXi Backup: Now you can restore a virtual machine assigning it a new name
ESXi Backup: Improved behavior with special configurations that could generate errors
FTP Backup with Zip Compression: Improved temporary files management
Several improvements and optimizations
Backup to Google Drive and OneDrive: Fixed a problem that in some cases prevented the software from making the synchronization
Dropbox Backup: Fixed an "invalid pointer" error when sending multiple zip files
ESXi Backup: Fixed an error in restoring a virtual machine to a different datastore
ESXi Backup: Fixed an error in removing snapshots on ESXi 4.1
Normal copy on disk and network: in some cases the software made again a full backup even if not necessary