friend of mine did it as part of a team that cycled from the lowest point (dead sea) to the highest point (everest) for charidee. (I don't think they actually cycled the last bit)
He's a pretty good climber and still very nearly carked on top. He'd already summitted and was descending, becoming badly disorientated and needing some convincing not to just bin his oxygen supply and sit down and wait until he felt better before descending, which would of course have seen to him as well (according to the report, there were 4 died on the mountain during the period they were there from other expeditions)
http://www.mounteverest.net/news.php?id=2115
Would I want to do it. Not on your nelly, although i can see why to others it is so appealing. And even though he's an ordinary bloke I was at school with, who I've seen singe his arsehair lighting farts on cadet camp and so on, I have a great deal of admiration for the achievement, which for a climbing sort must be just about the summit of all achievements. Not many of us will achiev that in our chosen careers or hobbies.