Russinovich is a deity with many of us, a true pioneer.
What's funny is NewSID was sooooo important over the years for ghosting, and his more recent commentary indicates that much of that did very little of it's intended use in the end.
Winternals was also some great stuff many of us have fond memories of, but MS scooped Mark up and they promptly died. The Admin Pack was a godsend. We have replacements for those functions now, but Russinovich will always be the king.
I've seen a few of his seminars in the Northwest over the past few years, always captivating stuff.
Sysinternals are fantastic, and they're just perfect single utilities, powerful and always leaving you wondering WTF MS STILL doesn't incorporate these into Windows as admin tools.
I'm just glad MS still allows Sysinternals to continue to develop and release for free, and from what I can tell, without any interference from MS.