A friend uses git to store his pictures.

Well played.

hmm interesting

Maybe not the best approach for big binary data, but why not.

I use git with a little mount magic, a small script and an external hdd as my personal backup tool.
All backup tools I found where big, complicated, need lots of configuration and you never know if you can trust in it's restore functions.

Git is easy, i know how to handle it and I know how to restore anything if I need to. For my personal data that's the perfect solution with a minimum of effort and a maximum of reliabilty.

I also tried that once, mostly because of the convenient push and pull. But I stopped using it because the deleted pics where still using up a lot of space.
I guess you have to do pre selection before checkin to make this usable.

"Open Source Images"

Interesting

@gnaaah Not deleting old stuff is the main task of a backup

makes for a good "yet-another-revision-control-system" project idea.

GIT for big binary data is a shitty idea.

Aaaand that's why there is git annex or git lfs ;)

Rather than pictures, I really need some solutions for version control on PowerPoint, Word and Excel files

Well... I use 'bup' for storing large filed, it works damn pretty well!

$ cd /
$ git init
$ git remote add origin my_repo_url
$ git add -A
$ git commit -m "Commit entire HDD"
$ git push -u origin master