The iPad is good for many things, and even running 'real' computers remotely. These apps allow accessing remote installations of Windows, Macs, and Linux systems, right from the iPad. They each bring a touch interface to any remote installation being controlled. Some of the apps don't require the user to have a remote system for access.
Remote desktop apps for the iPad
Don't miss the new app for Windows 8 Metro app developers that lets them test apps in progress on the iPad.