Using openssl to test https sites

Here is a little gem I found in Absolute FreeBSD - Chapter 9 that lets you test the certificate used by a web server to start a https connection. Basically what happens is that openssl opens a SSL connection to the web site, prints all the details of the connection and then you can enter a HTTP request as if you were connected via telnet to port 80. Reading the output gives you a good idea of what is wrong or right with your cert. Seeing I had to use it twice today to check our certificates I would say it is really useful.
Here is an example of use:

openssl s_client -connect www.google.com:443

Which yelds:

CONNECTED(00000003)
depth=1 /C=ZA/O=Thawte Consulting (Pty) Ltd./CN=Thawte SGC CA
verify error:num=20:unable to get local issuer certificate
verify return:0
---
Certificate chain
 0 s:/C=US/ST=California/L=Mountain View/O=Google Inc/CN=www.google.com
   i:/C=ZA/O=Thawte Consulting (Pty) Ltd./CN=Thawte SGC CA
 1 s:/C=ZA/O=Thawte Consulting (Pty) Ltd./CN=Thawte SGC CA
   i:/C=US/O=VeriSign, Inc./OU=Class 3 Public Primary Certification Authority
---
Server certificate
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----
subject=/C=US/ST=California/L=Mountain View/O=Google Inc/CN=www.google.com
issuer=/C=ZA/O=Thawte Consulting (Pty) Ltd./CN=Thawte SGC CA
---
No client certificate CA names sent
---
SSL handshake has read 1765 bytes and written 322 bytes
---
New, TLSv1/SSLv3, Cipher is RC4-SHA
Server public key is 1024 bit
Compression: NONE
Expansion: NONE
SSL-Session:
    Protocol  : TLSv1
    Cipher    : RC4-SHA
    Session-ID: xxx
    Session-ID-ctx: 
    Master-Key: xxx
    Key-Arg   : None
    Start Time: 1237496532
    Timeout   : 300 (sec)
    Verify return code: 20 (unable to get local issuer certificate)
---