A lot of my favorites don't post very regularly but, hey, that's what the archives are for. (It seems a lot of my professional peers are too busy running their companies to blog about it. There might be a conclusion in there somewh... oh look a kitten!)
http://www.alwinhoogerdijk.com/ <-- smallish European software company
http://thefloggingwillcontinue.com/ <-- CEO of Three Rings.
http://www.lietcam.com/blog/ <-- metrics + MMORPGs = hotness
http://microisvcentral.com/ <-- autocollected meta-feed of a bunch of small software companies (disclaimer: I'm in it.)
P.S. When I think "technically interesting" I think "useful for software businesses" not necessarily "related to producing computer code." If you're looking for Erlang tutorials and Audrino hacking skip this post.