Video: Helicopter with giant drop-down chain saw trimming trees away from power lines, bonus helicopter gallery

I'm not sure where this is, but it seems unlikely that this is in the US - can you imagine the regulations it would be violating?

Using helicopters (wiki) to lift heavy stuff into those hard to reach areas is pretty common - the Chinook can lift 14 tons. 

Speaking of moving stuff around, here's a Soviet MI-10:

And here's a M-26 lifting an M-10:

From Popular Mechanics, 1951:

And then there's this:

Go see the whole gallery of huge helicopters at Dark Roasted Blend.