Microsoft Certified Professional Magazine is directly targeted at those certified by Microsoft: http://www.mcpmag.com
Certification Magazine specializes in information for IT certified individuals: http://www.certmag.com
Windows & .NET Magazine focuses specifically on Microsoft technologies: http://www.winnetmag.com
Online Learning is a resource for professional training and development: http://onlinelearningmag.com
Computer magazine is developed by the IEEE (Institute of Electrical and Electronics Engineers): http://www.computer.org/computer/
PC Magazine is a staple for technology enthusiasts : http://www.pcmag.com