HTC "Make More Space" app updated with notification when space is low.

HTC "Make More Space" is an HTC Windows Phone 8 exclusive device designed to help you manage storage on the HTC 8X and 8S. "Make More Space" simply displays the storage as utilized by your music, videos, pictures. Tap on any of them and you're taken to hub so you can manage your storage by deleting unnecessary files. 

HTC has updated the app to version 1.5 with one feature that "inform user to remove contents or uninstall app when available phone storage space is low". The update is of course free to download in the Windows Phone Store.