Liverpool & Districts CAMRA have just updated their real ale pubs map which is available free in pubs that stock their magazine, Mersey Ale. It covers several areas: the city centre, Crosby, Waterloo, Bootle, North Liverpool, West Derby, and South Liverpool. With more than 100 pubs listed, it certainly gives plenty of scope for pub crawls, and I was surprised to find out how many pubs I haven't visited. There is a large advert for Caledonian, which is fair enough as they sponsored it, but as for the rest, there is a picture of each pub, the name of the road it is in, with a corresponding number on the map. It makes no comment on the types or quality of beer available - it's simply a list of pubs that sell real ale at the time of publication.
I think this is an excellent idea, but unfortunately not possible for my own branch (Southport and District) owing to its much larger geographical area. You can see the map on their website - find it here - and download it if you want, but I find a paper copy is much easier to use.