You can make really good milkshakes with frozen bananas, with some other things added for flavor. I like blueberry with coconut milk (or oil). You can make chocolate with carob powder or cocoa powder (if you can have those things). Hazelnut is a good flavor, so is almond. Of course you have to add enough water to get it to blend, but I think these taste really good. I've heard that you can put them back into the freezer to thicken them, although I haven't tried it so I can't vouch for if that makes it thicker or just icy hard.
If you have a little coffee grinder gizmo it can be made thicker and more like ice cream. You can also make ice cream with a champion juicer but I guess you don't have one (I don't either).