I’m surprised this hasn’t been mentioned.
Anyway, go to Ben & Jerry’s, get some free ice cream and register to vote. They usually sponsor a charity, but I’m not sure this year.
It’s also free scoops tomorrow night at Baskin Robbins. IIRC it’s one free scoop per person, from 6-10 pm. Maybe check their website for details. And I learned this through Snopes (it’s TRUE) which is a nice side benefit in the fight against ignorants. 
Here’s a link for the Ben and Jerry’s Scoop Shop locator. Each shop also indicates whether or not they’re participating in free scoops and voter registration today. Free scoops from noon until 8 pm.
Here’s a link for finding Baskin Robbins near you. No info on whether all sites are participating or not. 6-10 pm.