Basically, bigger orders, or lots of stuff on the side, etc.
At pizza places I generally go a buck a box.
I'm conflicted on takeout as I know about the operations of a number of places where the person packing the order often doesn't see a dime of any tips.
If I see who's packing my order, for instance at a standup takeout place with few tables and an open kitchen, I'll leave something explicitly for that person. Otherwise it may go right into the cashier's or owner's pocket. As someone who's been in the foodservice biz for awhile, trust me it happens more than you think.
Even on deliveries of big orders, say 10 pizzas, a lot of places have an honor system where if the driver gets anything over $10, the balance goes into a staff kitty to be split at end of the night. You know when a driver comes back in with, "Can you believe how cheap those creeps were only tipping $10 on a $180 order!", that that guy is simply ripping off the rest of the staff 99x of 100 as he pocketed more than $10.
Yes, I'm cynical. Comes from experience.
But when you get great service, acknowledge it, even if it's just words. Best customer service person I met this year was a tattooed woman with purple hair at a Pennzoil oil change place. If I still owned my cafe, I'd hire her in a second and told her that after she refused a tip.