The PKI page

One of the most comprehensive PKI link farms, including probably every CA on the planet, plus an exhaustive list of legislation and technical standards. 

XML.org Focus Areas: BPEL | DITA | ebXML | IDtrust | OpenDocument | SAML | UBL | UDDI
OASIS sites: OASIS | Cover Pages | XML.org | AMQP | CGM Open | eGov | Emergency | IDtrust | LegalXML | Open CSA | OSLC | WS-I