Vintage flashlights can add an immense amount of immersiveness to live action games as well as being cool little props in and of themselves. Unfortunately, examples from Ebay or your local antique shop can be a bit fiddly to get working. Not to mention their frustrating ability to burn through bulbs and batteries.
A thread over at Club Obi-Wan (registration required) points to this useful alternative: a vintage-style flashlight fitted with modern LED guts from Restoration Hardware. There are three different models, ranging from the conveniently small 2 cell handheld to the large "can be used as a bludgeon" 3-cell monster. Prices range from $18 - $29, which seems reasonable for such a niche product.
The smallest model also happens to be a screen-used movie prop. The linked thread identifies it as the flashlight used by Indiana Jones in the temple exploration scenes of "Indiana Jones and the Kingdom of the Crystal Skull". High resolution screen captures from the film show that it was just redressed it with a minor paint job to the grip area.