Yes, I do that, purposely get lost, and then use an iPaq with TomTom Navigator to get me home. Touch wood have not had the battery die before I got back to somewhere I recognised.
Pretty smart bit of kit for wandering on foot about unfamiliar towns and cities as well.
I understand they make an all-in-one specifically for motorbikes, dunno what it's battery life is like though.
I have an iMATE Pocket PC Phone with both TomTom and Destinator. Love them both.
As for getting lost on purpose? I can't do it. Not that I've tried, but if I drive/ride anywhere, I always know where I am. I would have to be in and start from a completely foreign place for me to get lost. I went on a trip to Rome/Paris/Portugal/Ireland and never got lost.
Plus, there's the time factor. I got too much on in the week to have time to get lost...
PS: I will use the GPS to confirm my cyclepoota's speed is accurate, but due to no safe way to mount a Pocket PC on a bike, that's all I'll use it for...