I used Bacula a long time ago. Although you would have to learn its architecture, it's a very powerful solution. It lets you do backups over a network and it's multi-platform. You can read here about all the cool things it has, and here about the GUI programs that you can use for it. I deployed it at my university. When I was looking for backup solutions I also came across Amanda.
One good thing about Bacula is that it uses its own implementation for the files it creates. This makes it independent from a native utility's particular implementation (e.g. tar, dump...).
When I used it there weren't any GUIs yet. Therefore, I can't say if the available ones are complete and easy to use.
Bacula is very modular at it's core. It consists of 3 configurable, stand-alone daemons:
- file daemon (takes care of actually collecting files and their metadata cross-platform way)
- storage daemon (take care of storing the data - let it be HDD, DVDs, tapes, etc.)
- director daemon (takes care of scheduling backups and central configuration)
There is also SQL database involved for storing metadata about bacula and backups (support for Postgres, MySQL and sqlite.
bconsole binary is shipped with bacula and provides CLI interface for bacula administration.