On ubuntu, lots of software can be installed from the launchpad ppa repository. The repository url has to be added to the apt sources list on ubuntu and then the software can be installed from the package manager like synaptic. However for Debian there is no such ppa repository. But since ubuntu is based on Debian and uses the same apt based package management system, in many cases its possible to use the ubuntu ppa repositories in debian directly.
On debian 7 the add-apt-repository command is available and can be used to add any launchpad ppa repository in a single command.
# add-apt-repository 'deb http://ppa.launchpad.net/shimmerproject/ppa/ubuntu quantal main'
The section titled 'Technical details about this PPA' will contain the deb urls for the given ppa repository.
The ppa shown above can be found at https://launchpad.net/~shimmerproject/+archive/ppa.
Older debian versions
On older versions of debian, if the add-apt-repository command is not available, the the repository can be added by manually editing the /etc/apt/sources.list file and adding the key with apt-key.
First import the key using the apt-key command
# sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 685D1580
The key can be found on the launchpad website under the section titled 'Technical details about this PPA'.
Signing key: 1024R/685D1580 (What is this?) Fingerprint: 424CFC4202CEA4C3FFB06DDAB22918DB685D1580
Check the signing key portion after the forward slash. That is the key to use in the apt-key command.
Next, add the deb line to /etc/apt/sources.list at the end
# echo 'deb http://ppa.launchpad.net/shimmerproject/ppa/ubuntu quantal main' >> /etc/apt/sources.list
Now update the apt cache and get the new softwares listed in synaptic.
# apt-get update