I use the ALL the time!
Store fresh fruits (berries etc) in them in the fridge - keeps them fresher longer
all grains and cereals - keeps them fresher longer
storing smaller pastas and rice
My larger ones (gallon) I use to hold ice tea in the fridge & to make Limoncello etc.
I thinly slice red onions one or two times a week and store them in quart jars in the fridge
all different sizes for left over storage
super small one for giving away homemade extracts
crafty supplies
oh and I would to canning jar "ramen" for work - bottom would be bouillon or ramen seasoning of choice, next few layers world be veggies (sturdier veggies would be precooked), then precooked noodles, then top off with any greens. Store in fridge. Time for lunch - just add hot water, shake up, and let it sit for about 3-5 minutes. So yummy!