To add one more in the list, Google Talk eventually became Hangouts. The list states that it was abandoned in 2013, but it was actually still working properly at the end of 2014 when I last used it. I don't know if it works any more, since I eventually switched to hangouts (although I was reluctant to do so - https://twitter.com/StathisG/status/530740696719060992).
For several years I was using Notepad++ (and before that PSPad) on Windows and Gedit on Linux, but I recently switched to Sublime Text 2 on both platforms. I also use NetBeans, mainly for coding in Java.
Postman - REST Client: This is actually an app and not just an extension, but I need to mention it since it's an amazing tool for anyone building or using APIs - https://chrome.google.com/webstore/detail/postman-rest-clien...
Web Developer - https://chrome.google.com/webstore/detail/web-developer/bfba...
Evernote Web Clipper: a must-have for anyone using Evernote - https://chrome.google.com/webstore/detail/evernote-web-clipp...
Speed Dial 2: yet another new tab screen replacement - https://chrome.google.com/webstore/detail/speed-dial-2/jpfpe...
LastPass: Switched to LastPass from 1Password, and I never looked back - https://chrome.google.com/webstore/detail/lastpass-free-pass...
Extensity: A quite useful extension to quickly enable/disable... other extensions - https://chrome.google.com/webstore/detail/extensity/jjmflmam...
Full Page Screen Capture - https://chrome.google.com/webstore/detail/full-page-screen-c...
JSONView: Formats and validates JSON - https://chrome.google.com/webstore/detail/jsonview/chklaanhf...