A friend and I say it differently. I pronounce the 'ei' like 'eye' and she says it like "hay."

Wow, I was just wondering this same thing today :p
I've been pronouncing it as if it were romanized japanese... but I'm sure that can't be right :p

I think you're right, blackstock. I have the 振込み card here from when I ordered RTK3, and the katakana for his name (on his bank account) it ジェームズ　ハイジック.

The name is most likely German, and in German, "Heisig" would probably be pronounced something like "Haitzik."

I would pronounce it
"Hey, what the hell was I thinking, spending all my free time trying to learn all this wacky Kanji... like gallbladder??... When I'm I ever going to need to write gallbladder to my japanese friends... Hey, Yuki... How's your sisters gallbladder?"

Just kidding, I love this book.

and... No, I don't know how to pronounce our fearless leaders name.

Oh sure, you say you don't need gallbladder now, but there you'll be, on a cold metal table in an emergency room in rural japan, and you won't know the word for your gallbladder, which hurts like a hot rusty knife was stuck in your guts, but you'll know how to write that your flesh of nightbreak is killing you.

I recognized it immediately for a German name, and thought of it as "High-sig." I wasn't in a Japanese-enough mindset to get it wrong, I guess. :/

I am German and the German pronounciation is indeed like "high - sig"... But if he is not German I guess it could be pronounced differently.

First of all: let's just presume the Heisig family crossed over to America from Germany or Switzerland at some point. Now that this is out of the way, we can indeed safely assume that it is pronounced like High-sig (Or as JimmySeal already pointed out: Haitzik, which comes close as well!). I don't think there are a lot of other options as far as pronuncation goes?

I have been and am going to continue to pronounce it "high-sig".

It's High-sig. I don't think I can answer your questions about him being German or not, but I can tell you it's most definitely "high-sig".

My professor at my college (He teaches Buddhism and some high level Japanese self-study classes) knows Heisig personally. In fact, he's currently working on a project with him. And when I talked to him about RtK, he was saying "Jim Heisig (High-sig)".