I can't think of anything that would use that much, but here's a few ideas that would use some:
Make soda bread. The Paul Hollywood recipe calls for buttermilk, but I find natural yogurt and milk mixed half and half does the job perfectly well.
Tandoori chicken. Mix natural yogurt with half teaspoon each salt, hot chilli powder, ground cumin, a crushed garlic clove and half a teaspoon minced ginger, and a squirt of lemon juice. Use it to coat four bone in chicken thighs. Marinate for a few hours then mix in some chipped potatoes, cover with foil, and bake at 200C for about an hour. Uncover for the last 20 minutes so it all goes a bit brown.
Stir a couple of spoonfuls into curries just before serving instead of cream. Gives it tang and creaminess.
Make raita to go with curry. Grate some cucumber, squeeze dry between kitchen roll then stir into a bowl of natural yogurt with a sprinkle of salt, a tsp mint sauce, a squirt of lemon and a decent pinch chilli powder.
Make a yogurt dip to go with Greek chicken. There's a good recipe in Jamie Oliver's 30 minute meals.
Whizz with fruit, ice and a splash of juice in the blender to make a smoothie.