Returning all items in Views for Dates with Start dates AFTER Now as well as no date set
You can use OR conditions with the filters, and have one group of filters checking for the date value, and the other one checking for empty date field.

You would end up with something like:

*Some filters group you probably have here*
AND
  Date &gt;= NOW
    OR
  Date IS EMPTY


Here is a post for some info on how to work with these - http://www.webomelette.com/drupal-views-filters-and-or-logic