Maglite Solitaire: small hulks
The Maglite Solitaire is a small keychain flashlight which is barely larger than a car key. As such you can easily hang it from your bunch of keys or take it with you in your pocket. However, don't underestimate this small hulk!
It produces a ton of light. In addition, you can focus the beam to make sure you can choose a wide, spread beam or a concentrated beam that can bridge a longer distance. Small but powerful.