Cisco has an entry level design certification called the Cisco Certified Design Associate, or CCDA. This is similar to the CCNA in that it is a foundational certification that goes a mile wide and an inch or two deep. If you have passed your CCNA and you are looking for the next challenge, take some time to consider the available options...
Specialize in an area of networking with Cisco's Voice, Security, or Wireless CCNA Certifications.
Take your CCNA level knowledge to the next level and focus on the CCNP
Focus on the design track, starting with the CCDA.
If you are interested in persuing the CCDA, there are some great resources to get started. First, check out the Tekcert articles section for writeups on the CCDA or on specific topics that align with exam topics. Also, check out the Exam Topics, CCO login required.