He reviews a freebie (Tube Map) and four at 59p (London Tube 09, London Tube, iTrans London Tube and London Tube Deluxe). In principle I love the idea of London Tube (which sounds similar to the Nearest Tube app at £1.19 for iPhone 3GS phones only) as it's the only one that used augmented reality so "using the iPhone's camera functionality you can see an arrow that points you towards the nearest Tube station. However, there is no departure board functionality and the 'points of interest' feature requires additional payment."
Andreas gives London Tube Deluxe his vote. What do you think? Have you used any others or ones with extra bells & whistles like the Tube Exits app?