There's no substitute for such first-hand local knowledge, of course, but if you are interested in planning your journey at a slightly higher level, the latest Google Maps mashup I've found provides a tube journey planner. Similar to the one offered by Transport for London, but faster. Plus it shows where the lines actually run, which is quite neat.
Incidentally, I notice that the iconic London tube map has made it into the final three for the Design Museum's Great British Design Quest, as supported by the BBC Culture Show. Of the remaining entries, I think it is going to get my vote – partly because it is so enduring.