Space Monger is a really useful little piece of software that shows you, visually, what is taking up space on your hard disk. It has a function that lets you zoom in to see what is taking up space in a folder, and it also lets you delete from it’s interface.
It’s available here and it is free. Thanks to werkema software for making this. One piece of advice though – if you don’t know what you’re deleting, don’t delete it randomly!