This is the fourth installment in Blogs to Watch in 2009. Here are four more blogs I find useful:

• Sramana Mitra on Strategy – Sramana is an author, entrepreneur, and strategy consultant, and her blog is an excellent source of insight on a wide range of trends in technology and business, from Software as a Service (SaaS) to design, collaboration, and clean technology. Here’s her interview on collaboration with Jeff Pancottine, CEO of eProject, and here’s a great piece on Design Collaboration in the Extended Enterprise.
• Headshift Blog – Written by Lee Bryant and the staff at Headshift, one of Europe’s most prominent social computing consultancies. Headshift did the design work for Wikipatterns.com.
• Strategies for Internet Citizens by Jon Udell – Jon’s screencast about the revision history of the Heavy Metal Umalut page on Wikipedia is still one of my favorite ways to demonstrate how wikis keep track of the evolution of information. Jon wrote the book Practical Internet Groupware and he currently produces Perspectives, an interview series for Microsoft.
• The AboutUs Weblog – AboutUs is the wiki-based guide to web sites on a wide range of topics. It’s a great way to find new websites, and if you’re the owner of a website, you can add an entry to About Us, or easily update an exiting entry for your site. Since it’s a wiki, all you have to do is edit your page, and AboutUs reviews every edit made to ensure accuracy and prevent problems like spam.

What blogs do you find useful? Which ones are you following in 2009? Leave a comment and let us know what other blogs we should be reading!