This plugin is useful in conjuction with any auto blogging plugin which automatically posts content to your blog but you don't have total control on number of daily posts. Basically you can set maximum daily posts allowed on your blog.

A plugin to allow administrators to limit the number of posts a user can publish or submit for review in a given time period.

Limit the number of posts or custom post types that can be published based on role (i.e, author) or user.