Here are some last minute options... no one will ever know that you just remembered this morning.
using post-it notes create a heart, and write something you love about the other person on each one. (I did a small on on our fridge!)
3D hearts by How About Orange
You can get creative, check the local newspaper for concerts coming out and clip it, there you go thats date #1. Maybe include a menu (can be found online) of a new place you want to go together, thats date #2. You could also include a momento of a previous outing like that pressed penny you made down on the waterfront, thats date #3. I could go on, you could also make the box for "a month of dates". Thanks Babes Ruth for the inspiration.
I'll admit, I don't have a heart cup cake tin, but I can still make heart cupcakes thanks to this great idea from Tastes Better From Scratch.
Strips of paper and a stapler, there you go - heart garland. You can also do it in other colors, metallic would be fun!