You can very thinly slice unripe plantains, not totally green, and fry them to make chips/crisps. Dip them in homemade mojo for a treat. They are available commercially in bags here, just like potato chips.
You can slice them thick, 1/2"-1" or thicker, fry them, then smash the 1/2" ones, fry and then salt. They can be dipped in mojo too. The thicker ones can be fried, sort of smash and form into a cup/bowl that makes a good vessel for individual ceviche, guacamole, etc.
Oh, you fry them like double fried French fries, at a lower temperature first, then higher.
Ripe ones, which are black or mostly black, can be fried and salted as a savory side. Have to be careful though because the starches have turned into sugars and they burn easily. I brine mine for at least an hour before cooking because I think they taste better that way. Just be sure to blot them dry and go easy on the salt after frying.
The ripe ones can also be baked with brown sugar and a little salt for a dessert sweet.