Hi S.,
Good luck on your pregnancy!
I would not recommend a "going out" type of certificate unless you're providing the childcare too. I know with my first we felt pretty house-bound for a long time (he was a tough baby) and if I'd had a restaurant certificate, it would not have been used.
Certificates for take-out ("healthy-ish" like Quizno's if fast-food isn't your thing) would be nice. If you would like to take up a collection and get something big, Delightful Deliveries and Lobstergram both have meals you can send to them.
The best gifts I got for all three kids was food - make them a meal, if you're still cooking. Something easy that can be frozen is good - like a lasagna, some kind of chicken-and-rice or chicken-and-noodle dish would work too. That has the bonus of being cheap, and you can double the recipe and have your dinner too!
Actually, if you're expecting soon, it's a great idea to start stashing away frozen meals for yourself. Just start making a double batch of your freezable meals when you make dinner, and store half of it for after the baby.