Databases

I started working with MySQL recently, and that sparked an idea in my head:
What kinds of values can a database hold?
Specifically, we live in a time where every person with access to a computer is amassing huge amounts of data (the pictures on my computer alone take up more than 100GB).

So what if it were possible to create a database that could contain more than just random data points? What if a database could contain whole files or folders? What if these files or folders could exist in multiple places within a database (all files are stored in a central pool, with symbolic links in the relevant tables)?
What would this kind of database allow in terms of uses? What could be done with this to make it compelling? What new features/use cases/scenarios etc. would this be good for?