WhatSize 5.0.2 is Lion 10.7 ready.
WhatSize is shareware tool that allows the user to quickly measure the size in bytes of a given folder and all subfolders and files within it. You would be surprised at how many useless files might be laying around on your hard disks. The files and folders are automatically sorted by size, with the biggest sizes first.
While the app is measuring a folder the user can browse the files within that folder and immediately see the size in bytes. Hidden files, cache files, directories will all show up with their corresponding size.
Once the measuring of a folder has ended the user can also view the information by filtering for particular file sizes or types. The user can also move unwanted files and folders in the corresponding Trash bin similar to the Finder’s Delete button.
You can also elect to remove those unwanted locales for languages you never knew existed. For those of us, using Solid State Drives, being able to thin the boot volume by a few extra gigabytes will be a good thing.
Developed in Cocoa, Objective-C, the application makes use of multithreading, low level UNIX file system APIs, C programming and Obj-C method implementation(IMP) caching to achieve speed, low memory footprint and stability, unmatched by other tools.