Alarm or reminder option on date fields.

Within a field config, we can already choose whether to have summaries, etc.  What if we could also choose to enable an "alarm" feature per date field?  For example, someone makes a field to record the "date for review," and they enable the alarm feature.  Within a specified time ahead of the date recorded in the "date for review" field, the assignee gets an email or in-screen reminder.  This could be useful for due dates, review dates, etc., and it could be managed within a user's preferences ("Always notify me of assigned due dates within 48 hours," "Never remind me of assigned due dates, " etc.).