How do I quickly find large files and folders on my mac? I need to free up space on my Mac and know there are a ton of hidden files that are eating up space (Logic for example downloads a lot of instruments... somewhere).

Is there any way I can create an interactive (or non interactive) tree map of my hard drive?

Here is an example of a tree map http://en.wikipedia.org/wiki/Treemap
try 

du -sh *  | grep -E "\dG"

to get all files and folders of size 1G and above. (Output will only show once du is done)