All the programs which you install using Synapatic package manger,apt-get,aptitude have a .Deb file in the following folder

/var/cache/apt/archives

This is very useful when you want to check which version of package is installed on your system and you can take backup of this folder and install all the packages in another machine

If you want to use GUI Program for this check here: http://www.ubuntugeek.com/create-backup-of...-in-ubuntu.html

... And if your short of disk space then you can delete them all, which will make a lot of room ...

Besides, to check the verions you can use the synaptic package manager and you can also use synaptic to make a file that keeps record of all the programs that are installed.

What would be more interesting, is a program that saves all your preferences...

But then, if you know that all your preferences are stored in your home directory (the dirs with names starting with a . ) you can make an archive of this and everything will also be "backed up" :-)

That's often the problem with linux distros as Ubuntu, they 'r so logically build that you search for programs that can do it when you can do it yourself with 2 clicks