RSSOwl is a powerful feed reader application for Linux licensed under the Eclipse Public License and written in Java. To get it up and running in Ubuntu, all you have to do is follow the few steps below:
Install the unzip and sun-java6-bin packages:
sudo apt-get install unzip sun-java6-bin
With your user password. Next, download the .zip package from the official website (direct link here). Unzip it either graphically from Nautilus or issuing the command below in a terminal, making sure the current working directory is the one where you saved the rssowl-2.0-M9.linux.gtk.x86.zip file:
What you have now is an rssowl directory, which you can copy anywhere in your home directory.
To run RSSOwl, just run the script RSSOwl inside the rssowl directory:
Alternately, you can make a desktop shortcut to it. That's all.