Issuance Systems

e-Lock PKI
A certificate issuance system that is integrated with CryptoAPI. [Free] (e-Lock)
http://www.elock.com/

Entrust/PKI
A certificate issuance system for Windows NT, HP-UX, Solaris, and AIX. (Entrust)
http://www.entrust.com/authority/index.htm

pyCA
Python software for running a certificate authority on UNIX. [Free / Open Source] (Michael Ströder)
http://www.pyca.de/