Let say you’d like to sync all your projects between different pcs you own. Surely you can put every project on GitHub but this is not good for closed source projects (not if you’re using their free plan).
You can put the entire project on DropBox, but it will fill your space with .obj, .dll, .tmp, /node_modules/, … stuff you really NOT need.
The trick is to keep just a bare repository into DropBox: a well formed gitignore file will prevent you to sync object files.
So I create a GitBox folder into my DropBox folder, then:
git init --bare
git remote add gitbox "c:\DropBox\GitBox\MyAwesomeProject"
git add *
git commit -m "1st commit"
git push --set-upstream gitbox master