Google+1 - Add the +1 to your Chrome address bar so you can +1 from anywhere
Extended Share for GooglePlus - Share Google+ posts to Twitter/Facebook, etc.
G+ Notifier = Adds a Notification count in your browser status bar
Surplus - Google+ Features in your Chrome Toolbar including Notifier and account switcher
Hide the Google+ Notifier count
+Photo zoom = Hover over pictures in your G+ Stream to zoom them to larger size!
Google+ CSS Tricks - Various Optimizations. Read the notes on the Extension page though
Then there is the Comment Show/Hide Script, which I don't think is a full extension on the marketplace, so use on your own accord.
Google+ Hide Sidebars
Google+ Hide Comments - Show/Hide Comments so you can collapse them on long streams
Project - https://github.com/wittman/googleplusplus_hide_comments
Install - http://go.wittman.org/aua5