A great blog for beginner and intermediate -level users of Excel. Gregory Ropp has years of experience and is generous about responding to reader comments.
Daniel Ferry created this website to help people stretch what they can do in Excel at work and in life. His blog is comprehensive, his classes get great reviews, and he can be reached for consulting projects as well.
Jon's focus at the Peltier Tech Blog is on Excel charting. It's amazing what good data visualization can do.
Purna Duggirala created Chandoo as a side project in 2004 and in 2010 he quit his job to make it a full-time business. Nearly 40,000 members and 1,250,000 monthly page views make clear that he's delivering on his mission of helping people be "awesome in excel and charting."
Massive repository of Excel resources including templates, VBA macros, and more.