http://www.maximumpc.com/article/features/10_addons_you_have_know_about_google_chrome?page=0,1
the last 2 on this list.
-improve the "undo last closed tab" feature.
https://chrome.google.com/extensions/detail/bcennaiejdjpomgmmohhpgnjlmpcjmbg?hl=en
-improve how easy it is to use "Incognito".
https://chrome.google.com/extensions/detail/aaknjhenmanmibfigajllodbhkgdigbd?hl=en-US