There are hundreds of programs for any purpose you might imagine. Here's my collection of the best of the best and all of which are completely free, including my own desktop wallpapers and screensavers. No spyware, ad-ware, or viruses either. By the way, did I mention it's all free?

Internet, Computer, and Technology Information and News Websites

Anti-virus and Anti-spyware Programs

Communications: web browsing, e-mail, and chat

Media: image and sound creation and editing

Exploration: Google Earth, NASA World Wind, and Celestia take you where you've never been before.

Utilities: u·til·i·ty: The quality or condition of being useful; usefulness.
n. pl. u·til·i·ties
That says it all. Useful programs that make your computing easier.