Calendar Nav is a block with two modes.
The first mode 'Calendar' display a small calendar widget which highlights the public dates of pages which have the 'Show in Calendar Nav' custom attribute set. When clicked a highlighted day links through to a page defined in the calendar block's edit page.
The second mode, 'List' is intended for use on the page that is linked to from 'Calendar' mode and will display a list of pages whose public dates were highlighted on the date clicked in the calendar widget.
The custom attribute 'Show in Calendar Nav' is installed automatically with the block.
The calendar widget itself has Prev and Next buttons to navigate through the months.