Without a doubt, the first to come to mind would be Don Alm. I've seen his post(s) here and elsewhere, and I always consider them a "must read", at least for me. It's not just what he does (all his projects/businesses) that makes him interesting, but also the way he "thinks" and the fact that he's willing to lay it out for all to see and benefit from. To name a few others here I find ineteresting (since you ask)... Marcia Yudkin, Dien Rice, Bilal Babic, Mike McGroarty (visited his website, good stuff), Michael Ross, and hmmmmmm ... there's that one other guy, oh yeah, Boyd Stone, he seems to be a pretty interesting guy too.