At Space Access 2004 JP Aerospace presented on a new concept - using an ultra-high altitude airship as a platform for a slow ion-drive cruise to LEO. Sounds absolutely insane to me but here's the links...

http://www.hobbyspace.com/AAdmin/archive/SpecialTopics/orbitalAirship.html

...a brief summary with pics. Next are pics from the Conference itself - just scroll down...

http://rocketforge.org/twiki/bin/view/Main/SpaceAccessPictures

...the Ascender airship (stage 1, ground to the mesosphere) is already under development. The other concept is the "Dark Sky Station" which is a manned aerosat for use at ~ 200,000 feet. From there is launched the Orbiter - the presentation pics give very few details, but I imagine it switches from using gas lift to an essentially forced orbit once the gas pressure is too low.

What I want to know is how does it all fit together? Gas lift, aerodynamic lift, ion thrust, centrifugal force and high-speed drag. And how do they plan to power an ion-drive for such a thing???

If it works - beyond simulations - then it's an incredibly elegant approach to getting to LEO. But the extreme-altitude airship thing, by itself, is cool anyway.