Ted mentioned torches in the last show. I have got a battery/torch combo similar to Ted's. However, if I need a torch it's usually for something where I need to use both hands, so I use a headtorch. At this point I have to admit to a headtorch addiction: I think I have at least six. So I thought I would do a brief rundown of what's available.
Virtually all headtorches are now LED powered and run off 3AA batteries. Gone are the days of Petzl Zooms with halogen lamps, powered by those flat batteries. Just to show that I am a real torch nerd, somewhere I have an old acetylene powered caving lamp.
The Petzl eLite linked to is probably the smallest one I have. It runs off one of those button cells which hold charge for at least a year, so it shouldn't be flat if you don't use it for a long time. It's verysmall and can easily be fitted into a pocket, or included in a "Man Bag". I find it useful if I am staying in a hotel. If I need to get up in the night, rather than switch on the room light and wake SWMBO, I just click on the red beam, which lets me see where I am going without losing my night vision.
At the budget end of the market Alpkit https://www.alpkit.com/lighting is good value for money. The battery compartments tend to be a bit fragile, but can be bodged with gaffer tape. If you want something with more bells and whistles something like the LED Lenser series: http://www.amazon.co.uk/Lenser-Rechargeable-Head-Lamp-Black/dp/B001PMP340/ref=sr_1_16?ie=UTF8&qid=1454506552&sr=8-16&keywords=led+lenser are good.
More expensive torches have regulated outputs. The light doesn't fade gradually as the battery discharges, but maintains a constant output until it finally gives up the ghost suddenly.
Finally there are the very bright eBay ones. These run off LiIon batteries, so the usual caveats about them catching fire apply. I have something similar to http://www.ebay.co.uk/itm/131718046746 Living on a farm I need to do things like look for cows in corners of fields in the dark. This type of lamp will illuminate the corner of a field from more than 100yds away. I also use it for cycling, although on half power, as full power dazzles oncoming traffic. Battery life is around 2hrs on full power. Petzl Headlamps Elite '12: : Sports & Outdoors Petzl Headlamps Elite '12: : Sports & Outdoors amazon.co.uk