tracking disk usage on a Mac

When looking to track disk usage on a PC, I often use TreeSizeFree - which is awesome.  But I struggled to find something like that in a Mac.

I have used and like the trial of DaisyDisk.  It gives a graphical representation of all used files including hidden files and it can help you find things like Apple Mail usage or Outlook usage or itunes backups that can be eating up disk space within the Library folder.  

Superfetch causes 100% disk usage on Windows 8 machines

I was working on a Samsung laptop with Windows 8.1 where the machine's performance was subpar and I found that Task Manager shows disk usage was 100% (CPU and memory usage were normal).  When I opened resource monitor, I didn't see any programs using any more disk than normal.  Mostly from this page:
http://www.tomshardware.com/answers/id-2045646/windows-100-disk-usage.html

I decided to disable superfetch, which worked for me.  Disk usage dropped to single digits and would rise to 100% if/when the superfetech service was re-enabled.