Just because you can install so many high quality programs and applications from the Ubuntu Software Center does NOT mean that you should clutter up your computer with unwanted programs. I recommend that you investigate the programs you want to install first (on the Internet) so you will have a very "clean" running system that you will be proud of.
The LibreOffice word processor, spreadsheet, and presentation programs (file compatible with Microsoft Word® , Excel®, and Power Point®) come pre-installed whenever you install Ubuntu Linux. A LibreOffice drawing application and LibreOffice Formula also come pre-installed. If you wish, you can install the full-featured productivity suite, which includes a database. These applications have a high degree of compatibility with the Microsoft Office® suite. The native formats that LibreOffice uses are compliant with the Organization for the Advancement of Structured Information Standards (OASIS) consortium. In addition, they are compliant with an ISO/IEC international standard, ISO/IEC 26300:2006 Open Document Format for Office Applications (OpenDocument) v1.0. See Wikipedia.
Note: When transferring LibreOffice word processor files to someone who uses Microsoft Word (if you want achieve maximum Microsoft Word compatibility), I suggest that you save your files using the "doc" format for Microsoft Word 97/2000/XP instead of a newer format such as "docx". Close your LibreOffice word processor, then open your "doc" file again using LibreOffice. If there exists any formatting problems, they will usually be minor. Then correct them, and re-save the file as a "doc" file.
For photo managers you may wish to also consider ShotWell Photo Manager. (It may already be installed by default in your Ubuntu installation.) If you wish to install Google Picasca, if it is not offered in the Ubuntu Software Center, read about it here and download (and open it with Ubuntu Software Center) at this link for 32 bit Ubuntu and at this link for 64 bit Ubuntu.
For extremely advanced photo editing, you may wish to consider Gimp. Installation of a number of plug-ins available to Gimp further adds to its capabilities. For manual picture editing, it has similar capabilities as the professional edition of PhotoShop. However, it works very differently and takes a while to learn, especially since it opens with 3 interactive windows, which is very different. If you take the time to learn how to use it and go through the tutorials, you may be amazed by its capabilities.
For those who wish to use Skype, just install it from the Ubuntu Software Center and have fun. There are many other programs and games to add to your fun.
You may also want to install Stellarium, which provides "3D" photo-realistic skies in real-time, approximating what you would see with your eyes or binoculars.
I recommend that you install and use K3B for all CD and DVD burning. However, use ImgBurn for copying images from CDs and DVDs.
For those desiring programs for website building, computer programming (including programming languages), and science and technology, they are available here, and for free.