Netbooks are often thought of as just being "little laptops", but that is not the entire story. The rise of these ultraportable machines at a time when mobile broadband was becoming both more affordable and popular has arguably created a much closer relationship between these machines and the Internet, with consumers using them to check up on social networking sites, use web applications such as Google Docs and keep up to date with their email. The physical characteristics of netbooks, such as the small screens, have driven innovation in netbook interfaces up until now, but recently some alternative ideas have begun to surface about what a netbook experience should be like, with new ideas such as making web sites and social updates "first class elements" of your desktop. An interesting example of these new ideas in action is Ubuntu Moblin Remix.
A fun project that you can do with open source software and some carefully chosen hardware is to build yourself a media centre PC. This is a very different computing experience from a desktop or netbook, it can stream content from the Internet to your TV, act as a PVR, be a jukebox and stream media files to devices such as Internet radios in your home. When you connect a computer to your TV though you need a very different user interface to control it compared to a desktop or a netbook, everything must be visible and usable from ten feet away from the screen, content and functionality navigable by a simple remote control, and even content must be different, more video and audio focused and less text heavy. On Linux systems we're really lucky in having a wide range of media centre software options, popular choices include Boxee, MythTV, XBMC and Freevo. The problem is that these tend to run on top of desktop versions of Linux and certain functionality requires that you exit "set top box" mode and use a desktop or the command line.