I’ve compiled a list of shortcut keys for Google+ below. They really help you move through the interface and help avoid some display bugs that occur when just using the mouse.
My favorite one is when writing a comment, press Tab + Enter to submit the comment. Enter alone doesn’t work because it is used to perform a carriage return.
|J||Scroll down to next Google+ stream update|
|K||Scroll up to previous Google+ stream update|
|Pressing Q twice moves your cursor the search box in the “chat” section of Google+|
|Space||Scroll down stream by regular intervals|
|Space + Shift||Scroll up stream by regular intervals|
|Enter||When a stream update is selected Enter moves your cursor to the comment box|
|Enter + Tab||Submit comment|
|@||@ followed by a username is used to mention someone in a post or share the post with them|
|*||Use the * symbol to denote the beginning and end of bold text- *This would appear bold in Google+*|
|_||Use the _ symbol to denote the beginning and end of italics text- _This would appear in italics in Google+_|
|-||Use the – symbol to denote the beginning and end of |