Aaron Butacov

It adds a simple month-by-month calendar that shows all the months you have future posts for (and the current month no matter what), it highlights the days you have posts for, and as an added bonus if you click a day, the Post Timestamp boxes change to that day, month and year.
Also includes a widget so you can show users what upcoming posts you have on your website.
If you want to ad a widget to your dashboard, uncomment the line <code>add_action('wp_dashboard_setup', 'fpc_setup_dashboard_widget');</code> in the future_calendar.php file.

Future Posts Calendar

This plugin adds a monthly calendar that shows all the dates you have future posts.

rickacc

Linked Future Posts Widget acts very much like the upcoming posts widget by displaying 
scheduled posts instead of published ones, but includes a link to each post (using slug/post name). Requires WordPress 2.8+
Use this plugin in conjunction with the Future plugin from Marion Sudvarg to create a Post Grid of scheduled events and a list of scheduled 
events on the post page. Events that change from scheduled to published status will automatically be removed from the grid and list.
Linked Future Posts Widget is a derivative of the Upcoming Posts Widget plugin created by Aaron D. Campbell.

Linked Future Posts Widget

A widget that displays a list of scheduled posts with links to the posts.

Future Posts Calendar vs Linked Future Posts Widget