I've got this idea for some time and I was wondering if anyone has seen such a feature/app in any operating system and if you haven't, what do you think about it. Where do you think I should begin?

The idea is simple. I think we all have those files that are made and probably used for a few days and then are left on our disk and we never delete them or even check to see if we need them again. It'd be cool if you could right click on a file and click on "Expire in.. 3 days" for example. And the file gets deleted after 3 days. I have a great need for this and maybe some people will find it useful.

I was thinking of writing a script and use the Nautilus Action project in GNOME for a start.