I'm planning to walk backwards off Battersea power station (albeit it attached to a rope but still 100 feet drop...) to raise money for MAG :

MAG (pronounced "Mag") – Mines Advisory Group – is a neutral and impartial humanitarian organisation that clears the remnants of conflict for the benefit of communities worldwide. (further info in the box on the left).

If you rate what they do (and who wouldn't), I'd be grateful if you could give a donation (preferably gift aided if you're a tax payer), however great or small, every penny counts! 

Thanks very much, really appreciate it, and will post embarrassing photos online after the event for your amusement.

Annie x