Firefox with Greasemonkey: If you like seeing just your Google Calendar without all the sidebar clutter and widgets this simple Greasemonkey script puts a persistently maximised calendar interface a single button press away.
If you want to see your GCal and your GCal alone, Persistent Max Google Calender is a tiny Greasemonkey script that expands your calendar to the full size of your browser window — whether you're browsing in a tab or in full-screen mode — when you press the F12 key. You'll no longer see the Google site bar across the top, the search box, the mini calendar or the My/Other calendars list. All your screen real estate will be dedicated to browsing your calendar. Another F12 press and you're back to the traditional view.
Max Persistent Google Calendar is free and works wherever Firefox with Greasemonkey installed does. Have a handy script for tweaking your favourite online apps? Let's hear about it in the comments.