Ideas for cereal and smoothie toppings

Hello all,
Hope you're having a great day :h6)

I wanted to ask if anyone here has cold cereal, or overnight oats for example, I use all-bran or fiber cereals a lot of times for my complex carbs. It makes a surprisingly good and easy snack too!

I just wondered if adding a spoonful or 2 of a protein-rich nut butter or seeds, like adding sunflower seed butter could make a good topping. I'd like to know if you have any other ideas to make a plain bowl of cereal more interesting!