Take a look at the RF Link AVS-5811 if you need a better solution than the Terk Leapfrog (and similar) stuff.
The AVS-5811 sends and recieves on a 5.8 GHZ signal (4 user's choice frequencies). It does not suffer from interference from wireless phones, microwaves, or WLAN systems (unless, of course, any of them transmit on a 5.8 GHZ signal). It also appears to have MUCH more range.
I have tried most of the rest and would recommend this system to anyone... No, I'm not on their payroll, but I'd like to be. None of the local TV specialists have even heard of this system (I checked). Why they don't advertise more is beyond me.
Sorry I don't have a link, but Froogle AVS-5811, you'll get an idea of where and how to check it out...