Navigon have dropped the price of their MobileNavigator software covering the British Isles from £52.99 to £34.99 untill 11/01/10 (they seem to do this to coincide with an update to the software - version 1.4 has just been released).
As pointed out by 'ms01ma' and with thanks to 'starkey' for spotting the Morrisons deal, the price of this can come in at £24.99 if combined with the 2 x £15 iTunes vouchers for £20 deal, as discussed here: http://www.hotukdeals.com/item/549496/2-x-15-itunes-cards-for-20-00-morri
Seems to be one of the best navigation apps for the iphone.
MobileNavigator turns your iPhone into a navigation device with many innovative functions. The easy and and intuitive operation enables the menu to be operated safely. Whether you are in the car, on your bike or on foot.