I'm slowly in the middle of going through and removing all the crap that I have collected on my Mac to free up space and have came across The DeLocalizer. Which sounds cooler than it really is. From the site:
DeLocalizer will remove all non-American English localization resource files that you request. This application is geared towards American English users, as it will not remove localization resources for American English. Users that use other languages may still use DeLocalizer to remove languages that they do not use (except, of course, American English).
For me I removed nearly all languages, kept English(UK), French and Spanish and cleared the rest which got me back over 3gb of space.Another tool I am using is What Size, which crawls through any volume and will quickly measure the size in bytes of a given folder and all subfolders and files within it. This is handy for finding out like you iTunes folder is 25gb is size so it might be time to move it to external source!