GAND  A portable NeoOffice is coming soon.  
(Version 2.0.2 r1.0)

GAND  Yes, you need X11 to run OOo.  
(Version 2.0.1 r1.0)

GAND  Portable Gimp.app is the same of Gimp.app by Aaron Voisine with a little script change to make it "Portable". He write to me that all the gimp binaries are universal. The OS X application wrapper is ppc, but all it does launch gimp and pass it the names of files that get dropped onto the gimp icon. That means no rosetta performance hit when using gimp. You can verify this by opening terminal and running:

lipo -detailed_info //Portable\ Gimp.app/Contents/Resources/bin/gimp-2.2  
(Version 2.2.10-svg r1.0)

GAND  Gimp.app need X11. Portable Gimp.app means that you can have it on your portable drive, iPod or USB thumb, and run from it without install on the machine you are using. Instead, you have to install X11 if is not present.  
(Version 2.2.10-svg r1.0)

GAND  Try to archive Portable Cyberduck folder into a .zip file, copy it on your external drive, and expand the file on your external drive.  
(Version 2.5.5r1)

GAND  Thanks, it works also from a USB thumb MS- DOS formatted.  
(Version 0.88r2.1)

GAND  Porable apps were inspired by http://portableapps.com/ (win only).

All infos about OS X Portable app at http://www.freesmug.org/portableapps

I think you can find there most answers to your questions.

All apps relased are under GNU license and are unmodified binaries dowloaded form dev sites. Most developers are informed, and some of them collaborate to the poroject.

What make them portable is a script that open the app form external drive using a profile folder in the same external drive.

Please refer to Portable apps support forum:

http://www.freesmug.org/forums/portableapps

no registration required.  
(Version 0.88r2.1)

GAND  Try with HFS+ (Mac OS extended), there are probably some files in Adium app package that can't be copied on HFS format.   
(Version 0.88r1)