The Londonist has released a book of its favorite pub crawls, called The Londonist Book of Pub Crawls.
The description says:
An alternative guide to the pubs and bars of London, UK from the writers behind Londonist.com. Ten pub crawls take you to some of London's oldest, weirdest, most surprising and most beautiful drinking dens. From the real-ale pubs of Southwark, to the trendier spots in Shoreditch, and the literary dens of Soho -- it's all here. You'll even find a guide to drinking like Karl Marx who, as a young man, went on a famous pub crawl along one of London's most famous streets.
It's on Kindle, so you can have it for a song and get it immediately too.
You'll notice that it says "Volume I," so these guys are intending to release more of these. You can never have too many pub crawls.
Go here to get your copy for a little bit over a pound and a half.