Many people don't realize that you can get a free certificate for digitally signing and encrypting email. Thawte is one company that offers a free email certificate service. Once you have the cert its fairly simple to sign or encrypt email.

We recently renewed our code signing certificate for signing java applets, this is the first year we have had to renew it, and the process is a bit different from when we generated it. When we first received the key we did it with a CSR, and the java keytool.