Dice.com recently compiled a list of the skill sets most in demand among employers. The top 5:
Security - Employers often want to hire people who have earned the CISSP (Certified Information Systems Security Professional) designation (see www.isc2.org). Candidates need 5 years of hands-on experience before taking the exam.

Virtualization - The term refers to the practice of running multiple servers on a single piece of hardware, increasing efficiency and conserving energy.

Java EE - Sun Microsystems' (JAVA, Fortune 500) Java and its enterprise edition, until recently called J2EE, are the industry standards for developing online applications, so the Sun Certified Java Programmer (SCJP) designation is in widespread demand.

SAP - Most employers prefer candidates who have direct on-the-job experience with SAP (SAP), but "having the right credentials can make even experienced candidates stand out," the Dice.com report says.

.NET - Microsoft (MSFT, Fortune 500) has a variety of certifications, Dice.com notes, but "the most bang for the buck comes from the Microsoft Certified Professional Developer (MCPD)" designation, which covers Microsoft Visual Studio and the Microsoft .NET framework.