Gmail Tweaker Pro is an extension for Google Chrome. Its simply hides the invite and chat boxes using CSS.
Full Specifications
What's new in version 1.3
Version 1.3 added new screenshots and updated changes in Gmail's markup and back to hiding chat together with invites for the ultimate sidebar cleanup.
General
ReleaseMay 13, 2011
Date AddedApril 13, 2011
Version1.3
Operating Systems
Operating SystemsWindows, Windows XP, Windows Vista, Windows 7