Inqlude provides a comprehensive listing of all existing libraries for developers of applications using the Qt toolkit. Inqlude is run by the community and open for contributions.
Qt Certificate Addon
This is the start of some work to create a nice Qt-style API for creating SSL certificates. Unlike the QSsl classes in the QtNetwork module, it uses the gnutls library, but it automatically converts between the two, for example a created certificate is returned as a QSslCertificate.