I put my mouse dongle on a short lead, and this enables me to position it for the best reception without drawing it out from the tv very much. Mind you, it's just about on limits at 3 mtrs.
I've never heard of a remote monitor, but I imagine it would be a device that would sell well. The data rate is fairly high, but I imagine the signal strength would be the main factor unless there was amplification at the dongle end. Essentially, it would have to replicate the video card's output electronics.