CLiCk, Speak is an open source, freely available extension for the Firefox web browser. It is part of the CLC-4-TTS Suite of products, it features a mouse driven interface, and it reads web pages - hence its name. CLiCk, Speak is designed for sighted users who want text-to-speech functionality. It doesn't identify elements or announce events - two features that are important for visually impaired users but unnecessary for sighted users. It also has a simplified, mouse driven interface that is designed to be easy for users familiar with point-and-click graphical user interfaces.
Stellarium is a free open source science planetarium for your computer. It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope.