Portable apps for Linux?
Most of applications that use GNU tool-chain can be built from source like this:
./configure --prefix=[directory which will contain your 'portable' application]
make
make install
and then moved to different computer with compatible libraries.
Linux doesn't have registry many applications usually do not really need to be 'installed' they can be built from the source instead so making "My Specialy Portable © applications for Linux" is apsolutely pointless so I think nobody even cares about this.
Just look at the topmost answer for this question and you'll understand that stupid concept of making applicatins 'portable' 'usefull' just in the world of registry and proprietary applications with license management.
The ./configure trick will work for some applications. Many applications, however, encode the prefix into themselves and then use it at run time to find supporting files. They also need the ability to load their shared library files (although the LD_LIBRARY_PATH environment variable can be set to help with that). The result of this, however, is that the portable applications will likely not be very portable -- they will depend upon being at the specified prefix. This will probably work in many places (most modern distros mount media at /media/DISKNAME), but it does prevent the application from being truly portable and location-independent.
The net answer, therefore, is that making portable Linux applications, while not impossible, is rife with subtleties. I suspect that this is a major contributing factor to why it isn't done near as much as it is on Windows. Additionally, public computing facilities (where the bulk of the portable application benefit arises) typically do not run Linux. A notable exception is university labs, but you can usually install some extra software in your home directory there.
Linux for Travelers tracks this topic and has several tricks to get around the fact that there aren't (yet?) portable apps installs aimed at Linux - likely for the reason you mentioned: if you have install privileges already adding new applications is easy enough to not need using your portable ones.
- Install WINE and run the apps from PortableApps.com or elsewhere. This seems like overkill, but it does let you use a portable apps install you already have.
- Run Damn Small Linux inside your existing Linux install (e.g. on Ubuntu). This one is useful if you don't already have install privileges on a given Linux system.
HackToLive.org (maintainer of Super OS version of Ubuntu) maintains some portable apps for Linux:
http://hacktolive.org/wiki/Portable_Applications_(Linux)