I just came upon a site that talks about the various kinds/forms/branches of Necromancy. Now I do not know if this information is based on complete facts or not, but I guess that's also why im posting, so you(more expert) than I am can see for yourselves and leave any comments. I believe this is the most informative site on Necromancy i've found thus far.
Whilst browsing and lurking I "think" I found the head page of the site. It seems to be made poorly by html, though im not too sure for I know nothing about website design, but here is a more "informative" link: