I needed a GPS for the bike as I am now in France and getting lost here is quite easy. Looking at the TT and the Zumo I really couldn't aford the �150+ pricing especially as I already have a GPS for the car and a spare one from the missus's car.
So. I bought a bike bracket off Ebay for 99p and a crocodile clip lighter socket for �2.99 and a bluetooth headset for �8.00 and Hey presto it fits my spare Navman perfectly. Not waterproof I'll admit but a resealable freezer bag took care of that in the rain (which I tend to avoid anyway).
Brian