The iPod thing only works by downloading it over the net in realtime, so only works where you've got a 3g connection. I don't think anyone has done a Nokia thing like this.
With Viewranger you actually buy the maps, so you have them on your memory card. So if you've got no signal, you can still use it (like in large parts of the Peak District). Which is why it costs money.
Depending on where you ride, Viewranger national parks is cheap, and has most of the Peak District, lots of good Scottish riding etc.
Viewranger really is great by the way.
Joe