I was checking out some of the language links from MyChinaStart.com and found this site where you can look up Chinese characters and see where they came from. If you have some Chinese font installed on and English-only PC, you can copy the characters from charmap.
From this page, I find that there’s not just Minbeihua and Minnanhua, but also Fuzhouhua, which is described as “also very different [from the other two languages]”. Unfortunately, there are no further details.
(Thanks to Chris Waugh for the MyChinaStart.com link.)
[05.08.14. It’s worth noting that it’s possible to get historical character dictionaries which might focus on a specific style such as lishu or seal script, or which might list characters through the ages to show how they’ve evolved from one period to another.]