There are various options available for design related certifications.
1. IBM 486 certification on OOAD/UML however not sure whether this is still active. Please check IBM web site.
2. UML certification from Object Managment Group.
3. SCEA where you will be tested on design, analysis and design patters etc.
4. Other certifications like TOGAF.
Hope this helps.
Sai Surya, SCJP 5.0, SCWCD 5.0, IBM 833 834
http://sai-surya-talk.blogspot.com, I believe in Murphy's law.