I have the most respect for people doing the most difficult things, which are still "deep voodoo" subjects like gcc hacking, libc hacking, kernel hacking, even if those don't get the buzz these days.
Being a language geek myself, programming language hackers also get points, although out of a sense of modesty and awe with regards to big, fancy languages, I wouldn't include Hecl in that.
John Carmack and Erik Naggum
I'll throw out a few of my faves: Joel Spolsky, Adrian Holovaty, Avi Bryant, Cal Henderson, Andy Baio. And of course: Paul Graham.