timlinden

Remembering to post every day, and which days you already posted, is super easy with this plugin. 
It shows you a calendar with days red when there isn’t a post, and days green when there is. Green 
days you can hover over and see the title of the post, and click to edit the post for that day.

wpFutureCal

A simple calendar that displays when you edit posts, showing which days you have posted on.

Kaspars

tetele

This plugin can be used for defining an editorial plan. WP already does a great job with the Scheduled post status, but what if it could be simpler than that?
When publishing posts, the plugin computes the most recent interval when a post can be published and picks a timestamp in that interval when to publish the post. If the selected interval has already passed since the newest post was published and there are no scheduled posts in the queue, then the new post will automatically be published.
The plugin alters the default behavior of WP when publishing posts from the interface or using code (e.g. <code>wp_insert_post()</code>).

Automatic Post Scheduler

A plugin that automatically schedules posts depending on a min/max threshold and the last post's publish date and time.

wpFutureCal vs Automatic Post Scheduler