Mountaineer and philanthropist Gavin Bate, who is raising money for his charity Moving Mountains, has set up an eBay bidding page to auction off the chance to write the world's highest Twitter message to be sent from 29,000 feet above sea level.
Using a satellite phone, Bate has been detailing his ascent to the Mount Everest summit on microblogging website Twitter.
The auction offers "One Tweet of your choice (140 characters max), sent by Gavin Bate via satellite from the top of Mount Everest" and is currently bidding at €72 (£65) with three days to go.
Bate is calling for marketers and PR firms to get involved in the bidding to promote their brands.
Money raised goes towards Moving Mountains, which helps street children in Nepal and Kenya.
Bate is at base camp at the summit, below the South Col or "death zone", 26,000 feet above sea level. Weather permitting, he excepts to climb the summit between May 18-24.
Yesterday, American astronaut Mike Massimino posted the first Twitter message from space, as the Nasa shuttle Atlantis entered orbit. @Astro_Mike's Twitter message read: "From orbit: Launch was awesome!! I am feeling great, working hard, & enjoying the magnificent views, the adventure of a lifetime has begun!"
More details on Bate's myeverestchallenge.com website.