PBwiki's Calendar Plugin, through and from 30boxes.com is fairly easy, but it's set to show you a range of days in a fully 'rotating' Calendar field. If you scroll up, (or back in time) you will see past months. If you scroll down, (or ahead in time) you'll see the months to come.

Access it from the "Insert Plugin" > "Productivity" > "Calendar" toolkit in the Editor mode.

See below;