For example, when installing OwnCloud you may want to ensure that your personal files are being sent and received securely no mater where you are connecting from. OwnCloud has the facility to require all communications to be carried out over SSL which StartSSL is perfect for.
StartSSL provide a one year certificate for free. While the website is nothing to look at ( and may even cause you to wonder if the site is legit and still active) the most important part for a test or demo site is whether or not the certificate is actually trusted by all browsers by default. The good news is that StartSSL passes this test with no issues.
When I recently tested the I found the sign-up process to be quick and painless. Ignoring the fact that the service is free, the basic domain verification was carried out very quickly especially when compared to other vendors.
It should be noted that there is a $24.90 charge to have the certificate revoked (which should not happen if the necessary precautions have been taken)
Have a look over here to see how to generate the CSR and install into apache.