Let’s Encrypt is now in public beta phase. It allows you to create free unlimited trusted SSL certificates that work in all browsers (all relevant browsers anyway). There are now no excuses for adding SSL encryption to your website(s).
That isn’t to say that Let’s Encrypt isn’t without flaws: the certificates you can get are only valid for a maximum of 90 days. While you can of course renew them, if you don’t have some kind of automated way of renewing your certificates it can quickly become a pain to keep them up-to-date.
The other issue (at the moment) is that Let’s Encrypt own monolithic tool for requesting certificates requires to be run as root on your server, which no doubt some people will have issues with. Fortunately the protocol (ACME) used is public and alternative clients are available. I personally used letsencrypt-nosudo to issue my first certificate (this tool allows you to register an account with an email address with Let’s Encrypt, which might be useful) and intent to issue further certificates (and renewals) with the very simple acme-tiny.
If you haven’t set up SSL on your server before, these resources might also be useful:
I intend to use Let’s Encrypt for all my less important domains (which includes this site) until its reliability is proven and CheapSSLSecurity (Comodo PositiveSSL 3 years for $4.99/year) for the rest in the mean time. No need to pay any more.