If you don’t have Citrix infrastructure on the backend, then you’ll want to look into iTeleport. Which handles RFB & RDP connections.
Not a cheap app but will connect you to your windows, Linux or Mac desktops. Really want to watch Hulu on the iPad? Let your desktop stream it to you.
Ultra VNC was a good free app for remote controlling another PC. There was a Mac OsX browser version for controlling Windows machines, but I never used uVNC on anything but Windows networks.