Underused Insurance Benefits: What Surprises You?

Last week I realized I'm really not taking advantage of my health insurance like I should be. I'm a 25 y/o male about to move off my parent's insurance (Health, Vision, Dental) and seeing the price of insurance made me wonder what I could really be getting out of it.

I know of the standard coverage (annual physical, skin screening, teeth cleaning, eye exam, etc.), but what are your favorite things your insurance covers? What are your surprised that more people don't take advantage of?

I know every insurance plan covers different items, but generally interested!