There are a lot of interesting blogs writing about Sitecore. Here are listed some of them.
This is a very interesting blog mostly they blog about their biased opinions on Sitecore and architecture. Now and then there's also a few posts about actual development and tweaks in Sitecore.
The blog is written by Sitecore MVP Thomas Eldblom, and owner and article writer on this site Jens Mikkelsen
Brian Pedersen has been working with Sitecore for a very long time, and he mostly blog about the things he finds when developing Sitecore solutions on a daily basis.
Mark writes about his experiences and biased opionions about his findings with Sitecore.
Ales is a Solution Architect and has before that workes as a Sitecore developer and architect. His experiences are valuable and he write many interesting posts.
Alistair is a Sitecore MVP and may be one of the coolest Sitecore developers out there. He has created several tools for Sitecore including his commando prompt for Sitecore called Revolver. He writes about how to solve different Sitecore issues, and about how to use general coding principals such as automated testing etc.
If you are interested in Sitecore, you need to subscribe to this blog.
John may have the most active blogs on Sitecore. He writes about how to solve different issues in Sitecore and about new features in the new versions of Sitecore. Further he summarizes where to find the best documentation for Sitecore is found. If you are interesting in Sitecore development, you need to follow this blog.
Alexey is working as core developer on Sitecore. It is especially interesting to read his posts about the Sitecore API.
Christopher is a Sitecore MVP and he writes some very interesting posts about his findings and usages of Sitecore and how to build different tools and customizations of Sitecore
If you have a blog, you want to be listed here feel free to contact us.