How many times do you have to interrupt your TV viewing to setup a PVR to record a programme, or you're browsing the Radio Times app or see something in a TV listing and you think 'I must remember to record that..'
I think a great idea would be able to have some kind of remote control app on an iTouch/iPhone/iPad, smartphone or tablet that communicates wirelessly with your PVR, that allows you to look at the EPG and select programmes to record, without having to either turn the TV on or interrupt what you're currently viewing.
It could possibly be also done over the web, which your internet connected PVR can synchronize with. In fact, thinking even bigger, the service could be agnostic to hardware and use a common interface protocol designed to interface with any PVR that has the appropriate software.
Whoever the body is who manages the Freeview EPG could provide the functionality on that platform.
Something like this I think is now possible with Sky or Virgin, but I don't subscribe to those services.