Portable outdoor light
I do a LOT of night shooting and I use a heap of cheap, aluminium LED torches. I buy them for about $4 each at Crazy Clarks/Reject Shop (like a fine-and-dime?) - they've got about 8+ LEDs in the front and take 3-4 AAA batteries. I've got about a dozen of them, most of which I've mounted to little Gorillapod knock-offs and gelled in various colours with cellophane.
With the mounted flexible tripod, I can mount them anywhere - garbage bins, security screens, tunnel walls, odd bits of things sticking out of ruins, doorways...
...and I can use more cellophane or a Cokin ND filter to reduce the intensity of the light.
I also use my home-made LED orb tool for lighting odd spots where I can't hide a torch.
Here's a pic taken outside using a few of the little LED torches to highlight some key parts of the subject. It's been darkened in post to be a little more moody.