Custom Subscription Generator is a Plugin for WordPress that allows users to generate a customized RSS feed or email digest (which can be delivered on hourly, daily, weekly or monthly schedules) of blog articles based on Category. This plugin relies on wp_schedule_event() a WordPress built-in function.
Notice: This Plugin is still in beta (development) so it may have bugs that prevent it from operating as intended. Of course, if there are any issues that make it unusable as described we’ll gladly refund your money.
Note: A related Plugin, and favorite of ours, called MailPoet provides a similar functionality except that it is limited to allowing Administrators choose the subscription options of it’s subscribers rather than allowing the User to choose, at the time of subscription, what feeds they want to be subscribed to. Although we love MailPoet and use their Plugin on many of our sites.