When my wife calls me at work and tells me one of the computers or apps isn't working right, I can remotely see her screen on my tablet and help her figure it out.

I have a PC running an open-source media center hooked up to my TV. At a party on the weekend, when I needed to play Barrett's Privateers for the traditional drunken singalong portion of the party, I used my tablet's VNC viewer to start the song playing while I was standing on the front porch with the rest of the Midnight Choir