I have updated my plugin Auto-Close Comments, Pingbacks and Trackbacks with one feature addition.
You can now choose to delete post revisions. Selecting this option will delete all post revisions in your WordPress database. Post Revisions were introduced in version 1.6 and in my opinion are absolutely useless unless you operate your blog as a wiki. But, do you?
I also fixed a minor bug where the scheduled cron was not deleted when you reset the plugin settings to default.
Lastly, the plugin now comes with its own uninstall code. Deleting the plugin from the Plugins screen of WP-Admin will delete all options from the database.
Existing users can upgrade the plugin from within WordPress Admin itself.
Read more about Auto-Close or directly download it from the plugin repository.