If you're a freelancer, consultant or other professional who bills by the hour, eHour can help you track and bill for the time you spend on projects. It also has some multi-user capabilities suitable for small offices. Operating System: Windows, Linux, OS X
This innovative app adds a text editor to a calendar/to-do list app. The result is perfect for keeping a diary or making notes about upcoming events. Operating System: Windows, Linux
Makagiga offers the same schedule/journal functionality as RedNotebook, plus it adds a sticky notes widget and a feedreader. Other optional add-ons are also available. Operating System: Windows, Linux
Like several of the other options in this category, qOrganizer offers a calendar, to-do list and an integrated journal. However, this one also adds special student-focused features, such as a booklet for tracking grades and attendance, a timetable for tracking classes and an extra loud alarm in case you've dozed off while studying. Operating System: Windows, Linux
44. Task Coach
Unlike many similar to-do list managers, Task Coach allows you to break tasks down into smaller sub-tasks. It also allows you to tag and organize tasks, and it integrates with some of most well-known e-mail clients, including Outlook and Thunderbird. Operating System: Windows, Linux, OS X
If writing a novel is on your to-do list for this year, Storybook can help you get started. It keeps an overview of characters and scenes in one place, helps you organize your book and includes features to help you maintain continuity. Operating System: Windows, Linux, OS X
Planning to tackle writing a screenplay or producing your own film? This "all-in-one movie pre-production system" can help you write scripts, produce storyboards, and much more. It boasts more than 1.5 million users in 170 countries. Operating System: Windows, Linux, OS X
Have you always wanted to learn more about astronomy? Stellarium can show you the stars in the night sky as seen from any point on earth at any time—it's the same software used by many planetariums. You can use it to help plan your nightly viewing or just to learn more about the universe. Operating System: Windows, Linux, OS X
Like Stellarium, Celestia helps amateur astronomers explore the night sky, but this project goes one step further. It also lets you virtually "fly" throughout the galaxy and see how the stars would look from Mars, Jupiter or any other point in space. Operating System: Windows, Linux, OS X.
Short for "Genealogical Research and Analysis Management Programming System," Gramps is one of the best acronyms we've ever seen on an open source project. It's a professional-quality genealogical program with a very active user community and more than 1,100 pages of online documentation to help you trace your own family history. Operating System: Windows, Linux, OS X
Like Gramps, GenealogyJ is a tool for viewing and editing your family history, but it was designed for amateurs, not professionals. Java-based, it creates family trees, timelines, maps, reports and more. Operating System: OS Independent
51. Sweet Home 3D
Determined to spruce up your home this year? This app helps you create 2D and 3D layouts of your rooms, complete with a preview of how the finished product will look. Operating System: Windows, Linux, OS X
52. LenMus Phonascus
Phonascus is a music theory and aural (ear) training program for musicians of all levels. It includes a wide variety of audio and written exercises, as well as a score editor for composing your own works. Operating System: Windows, Linux, OS X.
53. GNU Solfege
You might not have been born with perfect pitch, but you can get better with practice. This app will help you improve your ability to identify and sing intervals, chords, scales and more. Operating System: Windows, Linux, OS X.
First, let's make it clear that this app is not at all about dating—the "score" refers to musical scores. ScoreDate aims to teach anyone the basics of reading music. Operating System: Windows, Linux, OS X
Yes, there's even an open source project for coin collectors. Numismatica stores data related to your collection in a MySQL database that you can access through a Web app. Operating System: OS Independent