I may have got a lot of the detail of this wrong, and corrections, especially pedantic ones, are welcome, but I thought Zythophile's idea of classifying beers by Venn diagrams was much superior to the periodic-table approach, so I've decided to give it a go. Rather than take on beer styles, this diagram handles dispense methods. One reason for this is that it's easier; another is to attempt to show that traditional lager and real ale have more in common that a lot of people think.
Many of the greatest German and Czech lagers, when served by gravity or air pressure, very nearly qualify as real ale even by the strictest CAMRA definition (if you get to drink them straight from the lagering tank, they actually do, but most of us aren't often that lucky). Depending on your approach to beer and/or opinion of CAMRA you might think that is pretty amazing or perfectly natural.
I realise this is old hat to some people, but it needs repeating. Stonch had a great post on the subject, which said it all better than I could, but his blog is now private so I can't link to it any more.