If you're working from home or around today, Z-Burger has an awesome deal: $2 burgers until 10 pm. There's no limit on burgers, which is awesome, and they actually suggest sharing with friends.
Toppings are free, except bacon and cheese.
Veggie and turkey burgers are $4 each as well. Here's the Facebook event for it. It's just valid at the Columbia Heights location at 14th and Park.
I'm a fan of their burgers, so I'll definitely try to stop by. The milkshakes are also pretty awesome, but maybe not a milkshake day today.