Was going to mention the wedding forums. Getting married next year so have been looking recently. While we are all loitering around AIBU moaning about all things wedding related and how rude brides are, they are gleefully giving out the opposite advice over there. Lots of lols and hun and encouraging bridezilla behaviour.
However even they recognise that STD cards are for guests only, and what's more only for full day guests. Would be rude to tell someone to save the date just for the evening apparently - tell that to this bride!