If you're going underground, why do you need bother about geography? It's not so important. Connections are the thing.
Harry Beck, designer of the classic Tube map
Transport for London provide several current official versions and two interactive variants of the London Underground network diagram or 'journey planner'.
The design has undergone constant tweaking, both to accommodate new stations and to clarify the network: if all of Transport for London's projects go ahead, these could be the maps of 2010 [mirror] and 2016 [PDF; mirror]; compare a projection from 1994. Harry Beck would have been amused by Ian McLaren notes some of the recent alterations, while A History of the London Tube Maps complements The London Tube Map Archive, both with full-size scans. Peter B. Lloyd provides detailed catalogues, scans and discussions [mirror]. Another version is a 1962 three-fold card. The lines are traditionally represented in different colours; colour-blind travellers may prefer a version substituting black-and-white patterns.
A striking innovation of the 1933 map was its abandonment of geographical relationships, hence the pedantic description 'diagram'.
The Real Underground
(originally by Sam Rich) uses Flash to morph between the schematic and 'real' map.
There are several geographical Tube maps around the Web:
I recommend the version by Simon Clarke
[mirror].
R. Gardiner of NYC London has
overlaid this diagram on a satellite photograph of London.
There is another geographical map by Nick Aster.
The most familiar version which claims to respect geography has been accused of just joining the dots;
this is available from The London Tube Map Archive above [mirrored
1|2|3].
Free geographical maps of each line and Zones 1 and 2 are available at
Wikimedia Commons.
Oliver Jenkins used the co-ordinates in the Wikipedia discussion to mash together
Un-Goo-Ground, plotting the lines on Google Maps;
there is an unofficial Tube Journey Planner using Google Maps.
Privileging the map over the territory is Ken Kilfedder's London Underground Map with Distance Grids which morphs the underlying space to fit the grid. In 1983 Paul Mijksenaar produced a compromise that attempts to follow geography only in the central area.
Simon Clarke also provides schematic strip maps for a number of lines, showing track, platforms and tunnels. The London Transport Railway Track Map from Quail Maps follows the layout in space except for clarifying intersections. Rod McLaren's Tube map with walklines purports to link the stations where it's not apparent that it's quicker to walk. Ian Dolby's version adds all distances between adjacent stations. Get a feel for the distance covered by the whole network with these spidery maps comparing subway systems of the world, presented on the same scale. Or if you'd rather stay in one place, TubeHotels is a Google Maps mashup plotting hotels around Tube stations.
The design has been surprisingly stable (except when physically manipulated) but alternative renderings do exist, the most novel being Quickmap's moving trains. (The Quickmap is available to buy on paper.)
Related to train frequency is passenger traffic: an attempt at visualising load by Rod McLaren. Oskar Karlin's Time Travel redistributes zones and stations according to journey time.
Talking Cities offers an ugly interactive redrawing, metroPlanet a blocky geographic version and Subway Navigator one with muted colours and smoothed curves.
One possibly useful variant is The Way Out Tube Map which shows the appropriate carriage to board for a quick exit at your destination. One of the posters advertising World Mathematical Year 2000 on the Underground provided a topologically equivalent deformation.
A common trick is to leave the diagram unchanged but rename the stations, most famously and entertainingly performed by Simon Patterson in The Great Bear, on show in Tate Modern. (The other Tate is advertised on a London Transport poster: David Booth's The Tate Gallery by 'Tube'.) Anna Oliver's reading contextualises this piece. Another artwork portraying the diagram is an oil painting by Alan Nazerian of Chicago.
As well as The Great Bear, there are other Animals on the Underground. For Dubliners, here is a Tube map inspired by James Joyce's Ulysses; for Time Lords, here is a sadly indistinct reproduction of Shaun Lyon's map of The Gallifrey Underground Railway (closeups); and for rock bores, Dorian Lynskey's Musical Underground is accompanied by pages of hysterical humourlessness.
Two maps, one from branding agency Myrtle [GIF | PDF] and a more recent one by Horst Prillinger, translate the stations into macaronic German. Thetube.com has genuine maps with captions (not stations) translated into twelve languages, not including German. Imagine if the Cold War had gone differently with the map labelled in Cyrillic reproduced in 'Uncle Joe Knew Where You Lived' [page 37 of the PDF]. Apparently, foreign guidebooks often redesign the map rather than seeking a license for TfL's version.
Not 100% worksafe are spoofs from the Have I Got 1997 For You cash-in book [mirror] and the astonishingly filthy Undergroans, owing a lot to Viz. One culture-jamming genius printed stickers to 'improve' the in-carriage Northern line maps, and another invented Brown Punk station. There's even a real board game based around the diagram.
Stefan Magdalinski used TfL's maps of current disruption to create '15 days of Tube Hell in 3 minutes'. After the July 2005 bombings, Jonny Nexus redrew the map minus the closed lines and stations; see also Charlie Stross' take on it. Cal Henderson's Interactive London Transport Map lets you remove lines one by one to clarify the diagram or rewrite history. There are '3D' versions of the diagram - not of the actual network - from Corey Clarke, Andy Hudson-Smith and Artifice9.
Which London Underground map are you?
Its format lends itself to any network (or, indeed, surface). The London Bloggers Tube Map uses it as a gazetteer of webloggers in Greater London. Underground London, including 'lost' Tube stations, is represented in a map at the bottom of an article from Heritage Magazine [mirror], while a sideshift in transport generates a map of motorways in the London area or the UK (the latter by Gerald Higgins). Martin Kay's Process Mapping by Tube and John Welford's BrainWareMap for Creative Learning use the diagram as a starting point for corporate and personal creativity (the latter even including its own Mornington Crescent station).
NB Transport for London has deemed several 'remixed' maps to be infringements of its intellectual property in the diagram. The same may apply to other versions linked from this page. Other transport authorities may or may not be more lenient. Use at your own risk. It can only be a matter of time before The Sponsored Tube Map becomes reality.
The standard text is Mr Beck's Underground Map by Ken Garland, a thorough account, bordering obsession; its coverage is preceded by No Need To Ask! by David Leboff and Tim Demuth and succeeded by Underground Maps After Beck by Maxwell J. Roberts. (afterbeck.com includes a necessary corrective to the many London Underground Map Myths.) Two academic papers take a semiotic and ethnographic approach, respectively: The London Underground Map: Imagining Modern Time and Space by Janin Haidlaw (Design Issues 19(1), Winter 2003) and Janet Vertesi's Mind the Gap: The London Underground Map and Users Representations of Urban Space [both PDF]. Travelling would be very different in text only.
Edward Tufte's Ask E.T. thread on the London Underground diagram is open for comments.