The Secure Shell (SSH) network protocol makes it easy to connect computers that are running Linux, share files, and remotely run applications. Along with an X server, it can make sharing a single computer simple on a home network.
In my home, my wife and I need to share a desktop computer -- often at the same time. The computer runs Slackware Linux, and we have individual user accounts, Thunderbird email profiles, Firefox bookmarks, and other documents. Linux gives us the ability to share the computer by using multiple X Window sessions, each on its own virtual terminal. But the computer has only one monitor and one keyboard, which limits us to one user at a time.