Useful transport sites

If you're new to London, the Transport for london site is here:-

www.tfl.gov.uk - it contains maps and a journey planner to get you from A to Z.

If you want to find a specific street and don't want to pay for an A to Z, then check out either:-

www.streetmap.co.uk or http://maps.google.co.uk

What's cool about the google maps site is that you can type in things like "pubs near sw19" and it will show on the map the location of the pubs, and on the left hand side, it will have the details of each of the pubs.

For finding train times, you can use www.nationalrail.co.uk.

There are websites where you can buy train tickets in advance but in general it's easier to buy them at the station. London tube tickets are the most expensive in the world, and for the money you get the worst run service in the world.

Some things are innovative on the tube, like oystercard:-
https://sales.oystercard.com/oyster/lul/guestProductConfig.do?method=display
which allows you to electronically swipe on tubes and buses (sadly not trains yet which limits it's popularity south of the river).
Given that a lot of people now have oystercards, the queues for buying paper cards from the kiosks are much less, so it's a toss up as to which is the better option