Well, someone has finally begun cataloguing these into a searchable database:
Just lookup the device in question, point the lookup tool to a running appliance, or feed it a packet capture or live network interface and it will provide any known private keys.
Once the private key is obtained, you can decrypt the SSL stream with tshark:
tshark -nn -t ad -r
Note: For successful decryption, the initial full SSL handshake must be present in the capture. A full SSL handshake contains ClientHello, ServerHello, Certificate, ServerHelloDone. If you only see ClientHello, ServerHello, ChangeCipherspec, this is a continuation of a previously established SSL session and cannot be decrypted as is.