This is the first public release of WP-Crontrol. It's a plugin that lets you manage the WP-Cron system and see what's going on there. This includes adding/editing/deleting cron entries, as well as cron schedules. That means if you want to run a backup fortnightly, you can do it.
Complete post here :
http://scompt.com/archives/2008/04/26/wp-crontrol-03-released
Download here :