The Navigon MobileNavigator installs full GPS-navigation and map material onto your phone, effectively turning your iPhone into a sat nav with full active route guidance throughout the UK and Ireland.
The only downside is the price. Priced at £37.99 until the end of June (it will then go up to around £60), it's certainly cheaper than buying a full sat nav – but still pricey to say the least.
The good news is that you will be able to try out a free "Lite" version, coming to the App Store soon. This will drop the active route guidance, but will allow you to view the latest maps, and show you all the points of interest in your area.
The app will work on 3G and 3G S phones, but will require the 3.0 software – just in case you haven't got round to downloading it yet.
Would you pay so much for a phone app? Let us know your thoughts in the comments below.