Google:
Official Google blog
John Battelle's Searchblog
Google Blogoscoped
Unofficial Google blog
InsideGoogle blog
MSN Search's blog
Yahoo! Search blog
Machine Learning in the Valley
Venture Evolved (blog by
engineer turned VC in Chicago)
Microsoft:
Mini-Microsoft blog
Technical Careers at
Microsoft blog
Raymond Chen's blog
Programming:
Jeff Atwood's Coding Horror
Security: Krebs on
Security
Alexis
Madrigal (The Atlantic)