I got a bunch of these little 2 dollar led lanterns about the size of your thumb once, thinking I'd just throw them away when the battery ran out.
They are the handiest bit of kit I think I've lucked onto, the battery lasts for days even on all the time.
They're great to tie over your bivi entrance, or near where you piss outside your campsite.
Yeah I'm raving now, but they're pretty fucking handy.