I can't add a comment to grawity's solution, so I guess I'll create a new answer...
grawity's solution seems to be incomplete. It worked because you had already "tried installing in /System/Library/OpenSSL/certs".
I installed OpenSSL from MacPorts (newer than the version included with my Snow Leopard install). This put a
cert.pem file in
/opt/local/etc/openssl/, which I could then point to with grawity's method. This is essentially what I did:
sudo port install openssl
sudo echo 'ca_directory = /opt/local/etc/openssl' > /opt/local/etc/wgetrc
sudo cat /opt/local/etc/wgetrc.sample >> /opt/local/etc/wgetrc`
Ain's solution probably would have worked for me as well.