I've been for some time learning chinese characters along with the Zheng Ma input method. I found it convenient for coming with Windows and being able to easily convert to my Dvorak touch-typing, as opposed to Wubi.
The only resource I ever found in english, and have been using extensively, is this pdf guide on scribd (thanks MEGATRON COOKIE whoever and wherever you are). Especially the table at the end. But sometimes I find it incomplete and I then have to spend minutes on end trying every possible alternate combination to get to my character. Some characters have provided me with at least half an hour of frustration and I recall one which I never got to type and just gave up.
I have always thought more material on Zheng Ma should exist in chinese (or in english, who knows), but alas, I have to get up to baidu searching skill-level first. So the chinese.SE proves the perfect opportunity to find out what's out there.