Here's an awesome site I found to get free SSL certificates. They are an unlimited number of single domain server certificates and S/MIME email certificates. They are not trial certs, they last "one to two years" and this is not a promotion. StartSSL is a verified CA and also issues Extended Validation certs.

The url is:
https://startssl.com/

From StartSSL's FAQ:
Code:
90.) Why are Class 1 certificates free?
 
The philosophy of StartCom is guided by the principal that our services are charged 
according to the effort we have to invest. Since Class 1 certificates are domain and/or email
 validated only and the process is performed mostly by electronic and automatic means,
 StartCom doesn't apply any fees for this type of certification. StartCom started the
 certification authority a few years ago with the goal to provide free digital certification and
 adopted a unique business model previously unknown in this industry.
This is not spam, I use these free certificates on my site all the time and I think others should know about this.