Take the food truck example: it seems like a good idea since you see so many of them. But if you look on eBay you'll see a graveyard of food truck businesses that didn't make it. It's hard, it's complicated and it usually doesn't pay off running a food truck. I'm not saying it can't be done, but it's much, much more difficult than most people realize.
Second of all, legality. You can't just sell something for profit, at least where I live. Same goes for donating the profits to a student group, which would possibly make you a charity, but here you still need a license for that.
Lastly, there's the marketing point of view. What sets you apart from Dunkin Donuts or Krispy Kreme? They deliver too, in more than one way.
I'm not trying to discourage you, but I am giving you a warning. Selling food for profit is not an easy venture. Let me put it this way: if you cook up a web app and something goes wrong, you get angry users. If you cook up a bad batch of donuts, you get sick customers and massive liability suits.
If you go ahead with this: make sure you get all your bases covered. I was unpleasantly surprised how much time, money and bureaucracy it takes to run a food business. Some people are obviously doing okay, but to me it wasn't worth the risk/reward.
Good luck!