Thank you very much for the large load of information and links, they are extremely helpful. I've been trying to find some sort of outline to begin with.
Despite living in Japan currently, it is actually very difficult for a beginner to distinguish any minor dialect differences between kantouben in the immediate region. At least speaking for myself, it is extremely difficult to distinguish between just common used slang that I am not familiar or with pronunciations that differ by person and that of an actual different subset of a dialect used in the kantou area.
As for Hokkaido, during my stay I didn't really notice many differences in the language compared to Tokyo. I covered the southern regions and didn't travel farther up north to areas like Wakanai, however it seemed very close. I thought maybe there would be influence from the Ainu, but there didn't seem to be any. I'm sure some words were different, but no major differences from what I saw. At least around the southern region. Hokkaido isn't exactly small, so I'm sure there may be other areas where dialects could be quite varied. As for the subject of Ainu, Nice Gaijin is correct in that it belongs in another thread entirely. However, it would be a fairly good thread I'm sure.
I haven't had much time to study much about the different dialects in my stay, but I will be traveling through the southern and mid regions of Japan for 3 and a half weeks, so I wanted to at least give myself a heads up before going there. Not that I can prepare for any of the dialects I would run into in the amount of time I have, nor am I at the level in Japanese to be able to handle any major differences yet. That takes a great deal of time.
Thank you very much for all the help! I'm surprised I missed the section on dialects in Wikipedia, I had checked but didn't come up with anything.