Celtx is a free, multiplatform, & global Firefox-based program that on one end handles the print formatting needs of scriptwriters, media & event producers, etc; and on the other handles planning and promotion of many kinds of complex productions.
(Most programs of this type cost hundreds or even thousands of dollars.)
It would be extremely handy to be able to carry Celtx around, most users wind up having it on several computers, with the resultant multiple versions of their work. It also is being used around the world by people who...well, aren't boring!:]
As it is Mozilla based, I'd think it was almost portable already. Some of its users are 'high profile'.