WordPress Cron Starter
Demo Plugin that shows the use of recurring functions in WordPress.
The code is well documented and will by default add a new Admin Page under the Dashboard section.
I've explained what we're doing in this post: http://wpguru.co.uk/2014/01/how-to-create-a-cron-job-in-wordpress-teach-your-plugin-to-do-something-automatically/
Note that much of the plugin code is based on my Generic Plugin Starter. The section that specifically deals with Cron Jobs is clearly marked though - just don't get scared by all the other bits in there.