Salesforce Certified Administrator
Certification Link:
http://certification.salesforce.com/
Certification Guide:
https://secure2.sfdcstatic.com/assets/pdf/misc/certification-guide.pdf
Release Exam Dates:
http://certification.salesforce.com/releaseexams
Types of Certification:
http://certification.force.com/pkb/articles/Public_KB/Maintaining-Your-Salesforce-Credential/?q=release+exam&l=en_US&fs=Search&pn=1
Exam URL:
https://www.webassessor.com/wa.do?page=publicHome&branding=SALESFORCE