Ubuntu for astronomers

Fortunately, for us novice astronomers, Ubuntu and other flavours of linux do indeed give us a few nice and cool tools for basic astronomy. Unfortuately, they are not much. But anyway, like most Ubuntu software, the best thing is that they are all free. Here I cover a few of my most beloved software that can be put to good use for astronomy.

• Celestia: Name is enough, folks. I don't think celestia, the beautiful space-simulator, needs much introduction. It is arguably the best space-simulator I have seen in ages. Assuming that some of you might not still be familiar with this beautiful software, it is a simulator, i.e it generates a 3D model of the observable universe right on your desktop. Change it to fullscreen, master a few keystroaks and you're all ready to go. Another good thing is that you also have a large collection of free add-ons from the Motherlode (http://www.celestiamotherlode.net/). Ranging from our goold planet earth to 2004 MN4, you can get pretty much anything within the Solar System and much more. And while the precision might not be very great without the add-ons, you can always pretend to prophesise the doomsday. :D
• Stellarium: This is a good space-planetarium software, with loads of nice features. Besides, you can always set the time and date, or even another another earthly location to check what the sky looks like from there. Other than good constellation art and graphics, it also allows you to pause, forward or even backward in time. The star-arts are very detailed, and it also helps you checkout what the current phase of the moon is. It also features a few nice add-ons. 
• Kig: This is again the mathematical software, but you can put it into effective use if you plan to view the space geometrically. You can setup orbits of planets comets etc. and view the Solar System in a 2D way. While there is no automation like celestia or stellarium, you're free to calculate trajectory of a planet and virtually anything depending on your geometry and math skills. A simple mathematical model is always the key to victory!
• Kmplot: This is again another mathematical software, for plotting. You can use it to plot various star-charts, see where the solution leads to and so on. For example, calculation of Goldi-locks region can be helpful with a required set of data. 
• Zim/Gnote: Depending on your taste, you can always use a virtual notebook for storing data about important events and findings. My favourite is definitely Zim, with its vast set of features. Otherwise, Gnote/Tomboy can be pretty good too. 
• Maxima: For very advanced levels of calculation (relative to my current level) concerning astronomy, and if you're really deep into astronomy, you may consider using a CAS (Computer Algebra System). And as for Linux, Maxima (or with its GUI wxMaxima) can easily be called the best. There are other players such as Genius Math Tool, Mathomatic etc. but nothing matches the swiftess of Maxima.
• Freemet/Octave/Skylab: For engineering calculations related to space. They can also be useful to manage large chunks of astronomical data. 

Well, folks. This much for now, and please be sure to help us with your recommendations, if you are aware of some more cool utilities. Till then, happy stargazing!