Web Component Developer exam, as name suggests, tests knowledge about designing, developing and deploying web applications using Servlets
. It is more logical to take this exam after SCJP unless you are/want to be only a desktop application developer.
Certifications in general are an opportunity to refresh subject knowledge which in turn help you to do your job in a better way. Of course, they always look good on your resume.
I have been working in Java
web development for the past 6 years. When I prepared for my SCJP (new version), in Feb, I was surprised to see many subtle issues that were not on my radar.
[ April 17, 2007: Message edited by: Sri Kan ]