Something my husband + I do on occasion is record short videos talking to our future children. We're planning to save them up + then gift them to our kids once they're grown to give them a glimpse of what our lives were like before they came along.
Technically, the gift isn't specifically for a spouse, but it's a really sweet bonding activity for us to do together as we dream about the family we're going to create + prepare ourselves for parenthood. Plus, I'm sure we'll be laughing at our own silliness when we go back through all the Parent Tapes to put them together for our kids.