Similar to Microsoft's Visio, Dia helps you create org charts, network diagrams, flowcharts and similar types of documents. It creates XML files by default, but can also export to EPS, SVG, XFIG, WMF, PNG and some other graphic file formats. Operating System: Windows, Linux, OS X.
Similar to Adobe's Photoshop, Gimp is a photo manipulation program that's full-featured enough for professional photographers and graphic designers, but user-friendly enough for amateurs. Key capabilities include a full set of painting tools, sub-pixel sampling, powerful gradient and blend tools, full alpha channel support, layers, quickmask, transformable paths and more. Operating System: Windows, Linux, OS X.
Like Adobe Illustrator, CorelDraw and Xara X, Inkscape is a professional-quality vector graphics drawing program. You can use it to create your own logos, technical drawings and other types of artwork. Operating System: Windows, Linux, OS X.
Used by millions of people, Pidgin lets you chat with friends on 16 different IM networks, all at the same time. It supports many of the features unique to the different networks it supports, and it has a large library of plug-ins that extend its capabilities further. However, it doesn't support OS X. Operating System: Windows, Linux.
For those using Macs, Adium offers most of the same capabilities as Pidgin. Operating System: OS X.
24. Simple Invoices
Available as a Windows desktop download, in a Web server version or in a hosted cloud version, Simple Invoices makes it easy for very small businesses or organizations to bill their clients. It's browser-based, includes reporting capabilities and sends invoices as PDFs for a professional look. Operating System: OS Independent.
Argentum offers a slightly larger feature set than Simple Invoices, for those who also want to track client billing and shipping information, employee time, do simple budgeting and more. It's also available as a free download or in a paid hosted version. Operating System: OS Independent.
Mind-mapping software makes it easy to create diagrams that show the relationships between ideas and words. It's a great tool for brainstorming sessions, project management and outlining long documents. Operating System: Windows, Linux, OS X.
You don't have to be on your own PC to use your favorite open-source software—PortableApps.com packages many of the most popular apps so that you can take them with you on a thumb drive. The standard suite includes Firefox, OpenOffice.org, Pidgin and nine other apps, but dozens of other portable open source apps are also available on the site. Operating System: Windows.
RedNotebook combines a calendar with a free-form journal for keeping tracking of upcoming events or recording your thoughts. Features include searching, templates, word clouds, automatic saves and more. Operating System: Windows, Linux.
29. VLC Media Player
One of the most popular open source multimedia players, VLC plays most audio and video files, CDs, DVDs, streams and more. It also includes some helpful file conversion tools and a streaming tool. Operating System: Windows, Linux, OS X.
An open source alternative to Apple's iTunes, Songbird helps you mange, play, purchase and sync your music and video files. It comes in both a desktop version and a mobile version for Android devices. Operating System: Windows, Linux, OS X, Android.
Recently moved from Oracle's management to the Apache Software Foundation, OpenOffice.org offers an open source alternative to Microsoft Office. It includes word processing, spreadsheet, presentation, graphics and database software, and it reads and writes to Microsoft Office file formats. Operating System: Windows, Linux, OS X.
32. LibreOffice When some developers became unsatisfied with Oracle's handling of OpenOffice.org, they created this fork. It includes all the same functionality and programs as OpenOffice.org with some slight modifications and a few additional features. Operating System: Windows, Linux, OS X.
If your children use your home office PC to write school reports (and of course, they do), you may want to check out WriteType. It's a word processor with special features for young students, like word completion, read back, highlighting, grammar and spell check, and more. Operating System: Windows, Linux.