Image via Wikipedia
The Inland Taipan, also more hysterically known as the Fierce Snake, can be regarded as the most venomous snake in the world. They have an LD50 (Lethal Dose 50% or Median Lethal Dose) of 0.025 mg/kg. This means that it takes this snake 0.025 mg of venom to kill 500 grammes worth of mice.
While their venom is certainly Fierce, the snake itself is quite shy and reclusive. There are no reports of deaths at the fangs of the Inland Taipan and all bites seem to have been inflicted on people studying them. Sure, these are people who say "hey, there's the most venomous snake in the world. Let's go pick it up" but they are also just the kind of people who carry antivenom and know how to use it. Phew!
More on the Inland Taipan and the LD50 of various snakes.