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.
Dropbox is a free service that lets you bring all your photos, docs, and videos anywhere. Any file you save to your Dropbox is accessible from all your computers, mobile devices, and even the Dropbox website.