Extended Share: This extension lets you extend Google+ to share to Facebook, LinkedIn, Twitter, and more.
+Photo Zoom: Provides fast and simple zooming for photos within your Google+ Stream. Just hover over the image you wish to zoom and +Photo Zoom will load the enlarged version of the picture.
Replies and more for Google+: It will add reply and reply-to-author buttons to Google+ comments and a number of other enhancements.
Surplus: Google+ Integration for Chrome.
Google Translate for G+: Translate your Google+ stream using integrated, inline, Google Translate support.
G+me: Collapses the Google+ stream while keeping live updates. It collapses posts, hides comments, etc.
Usability Boost for G+: Greatly improves readability on Google Plus, ability to star posts to read later and some other useful features.
Google+ Ultimate: This extension adds functionality and theming for the site.
Google Plus Directory: Find your G+ is a Google Plus person directory, where you can meet new people, start making new friend circles and more for Google+.
-1 Minus One for G+: Minus one (-1) button in Google+ (Post & Comment) notifications.
More for Google Plus: Loads more content as you reach the bottom of the Google+ page.
Google+ Tweaks: Tweaks to the layout and features of Google+. Full width, thumbnails only, etc.
Notification Count for G+: Extension for displaying unread notification count for Google+.
Helper for Google+: Add extra functions to Google+. Get desktop notifications on new posts. Share Posts via twitter, translate posts with Google Translate, and bookmark posts for reading later, linked #hashtags, search in posts and profiles directly from your omnibox.
G+ Count in Title: Adds notification count to the document title in the page tab.
+1 Button: Plus one every page you like with only one click, directly from omnibox, without any annoying popup.
Uncircle+: Google+: Find and Remove Inactive People in Selected/All Circles. Inactivity = No Public/Private Posts at all or since a chosen date.
+Everything : Adds the Google+ bar to all websites.
[Thanks Gabriel Vasile]
