What is ?

[Batfish]

I have a non-nerdy ( :) ) note to add to this thread.
There's a show called Mythbusters on the Discovery channel here. They regularly take urban legends and myths and try to prove them wrong or right.
One urban legend is that a bundle of balloons at a fair floats a child away when they're all handed to the kid.
Mythbusters tested this by seeing how many balloons it takes to get a 40lb item off of the ground.
It took them about 3,500 balloons inflated over about 5 1/2 hours before they could get a 40lb item to lift from the ground.
They found that 10 party balloons would lift 100 grams.

What I took from the show is that helium really doesn't have as much 'lift' as we'd like to think :)