I love this type of utility - on any platform - showing at a glance where all your disk space has gone - absolutely invaluable when having a tidy-up! FolderPie does exactly what it implies, though actual deleting of files is left for whatever application is associated with the file in question - so this isn't a full management solution - yet!

From the AppList description:

Where have your mobile storage space gone? 

FolderPie can help you collect each folder actual size on your storage space. 
And present in Pie view for easy understanding at glance. 

A few screens of this in action:

Starting out at the disk level...

There are textual and graphical (pie) summaries... Tap through each to dig down a level in a folder structure...

As you dig down, you get to the file level, though the only delete functions are currently in whatever application you end up in.

Hopefully the AppList Store is working out for you all. See here just in case you haven't already got this installed or if this is new to you. Also, if you have custom firmware installed, make sure you tick the option in settings to show 'unsigned' applications, you'll see extra applications!