I like to keep my resume to two pages, and about a third of the second page is a listing of my certifications. Here's a copy and paste from my current resume (
warning: occurrence of me blowing my own horn ahead):
IBM Certified Associate Developer – Rational Application Developer for WebSphere 6
IBM Certified Application Developer – Rational Application Developer for WebSphere 6
IBM Certified Solution Developer – IBM WebSphere Portal
IBM Certified System Administrator – IBM WebSphere Portal
IBM Certified System Administrator – IBM WebSphere Application Server
Oracle Certified Associate - Java 7 (OCAJP)
Sun Certified Java Associate (SCJA)
Sun Certified Java Programmer (SCJP)
Sun Certified Web Component Developer (SCWCD)
Sun Certified Enterprise Architect, Java EE 5 (SCEA)
Microsoft Certified Systems Engineer - Windows NT (MCSE)
Microsoft Certified Professional + Internet - Windows NT (MCP+I)
Microsoft Certified Professional – Windows NT (MCP)
However, before the list became long, and I only had a couple, I would list the certification and then add a line or two about the cert. So here's how I would describe my Microsoft cert when it was the first one I got:
Microsoft Certified Professional – Windows NT (MCP)
-> achieved Microsoft’s premiere networking designation in late 1998
-> scored above 900 on all NT operating system exams, with a perfect 1000 on NT Server
I usually create a heading for "Professional Certifications"