I love the jar of fun idea! Another idea that works well for a single day is for each of you to write down 6 things you want-either new things to try, things you want more off, etc-and then, waiting until he doesn't expect it and is distracted by something else, hand him a dice and tell him that whichever number he throws, you will do what's on his list...the best thing about this one is that he then does the same for you
Here are some of my fun ideas...
-have a bubble bath together
-give him a "trim"-sounds a little weird I know but its very intimate and exciting, just be careful with the scissors!
-go on a picnic, but sneak something naughty (like a g-string) into the basket to get him excited
-take some sexy photos of yourself (if you trust him!) and leave them for him to find when he gets home from work