If you already dont know about getdeb.net, it is a great site to download the latest software, not many people know this but you can use getdeb's mirrors as repositories to sync your GetDeb packages with the update manager and Synaptic.
1. Open up a terminal (applications>accessories> Terminal) and run the following:
sudo echo "deb http://ubuntu.org.ua/ getdeb/" | sudo tee -a /etc/apt/sources.list
deb http://mirrors.dotsrc.org/ getdeb/
If I were you I would ping each host to see which is closer and add that one
Save the file and exit.
3. Now run the following in the terminal:
sudo apt-get update
sudo apt-get upgrade
Now you should be able to install GetDeb.net programs through the Synaptic package manager as well as apt.