Poco

This plugin installs a widget for showing a Google Calendar agenda on the sidebar. 
Once installed it adds a sidebar widget called ‘Google Calendar’ that may be dragged into your sidebar. 
Each widget can be configured with a ID of the calendar feed, a title, and the number of agenda items to show.
The calendar feed ID is the ID next to ‘Calendar ID:’ in the Google Calendar settings.
Multiple widgets can be used on the same page and each one can reference a different feed.
See also <a href="http://notions.okuda.ca/wordpress-plugins/google-calendar-widget/" rel="nofollow ugc">http://notions.okuda.ca/wordpress-plugins/google-calendar-widget/</a>

Google Calendar Widget

This plugin installs a sidebar widget that can show the upcoming events from a Google Calendar feed.

Cerzky

FullCalendarJs allows you to save multiple XML feeds into a calendar id and display those calendar’s as if they were one. 
The plugin works specifically off of a jquery plugin. The Jquery plugin is written by Adam Shaw. This plugin is lightweight 
 and is designed for ease of use and simplification. Why bloat your own database with calendar events when you can fetch 
 them all from Google Calendar.
More features to come.
Settings Page: 
* Settings > Full Calendar Settings
Shortcode: 
* [fcal id =”1″] //shows calendar of id 1 in the page or post

Full Calendar Js

Display multiple Calendar XML feeds into a jquery calendar. Works with Google Calendar and others.

Google Calendar Widget vs Full Calendar Js