Good Keigo Materials?

[yuriyuri]

The only place I have really learned about honorific and humble forms so far is here:
Honorific and Humble forms - Tae Kim's Japanese grammar guide

Since I've not been learning for long I haven't really looked any further into it than that 1 page I just linked above.

(It mainly talks about verbs, like for example the おV-stemになる type stuff you mentioned in your OP KyleGoetz)

But it at least got me understanding the very basics of how much politer language works.
And there's a nice list of some exception words too.
(Although obviously he doesn't go into too much depth about it, it is only a basic grammar guide after all)

I can't really recommend any books since I've never used any.