Via Hacker News. WoSign, a Chinese Certificate Authority, is offering multi-domain / SAN SSL certificate for free for up to 2 years, allowing up to 100 validated domains to be bundled into a single certificate. Not sure whether it has always been free (doubt it), but a free certificate would be useful before Mozilla's Let's Encrypt is live later this year.
Purchasing it could be a bit tricky because the site is entirely in Chinese and pretty slow from Aust. Freerk Ohling's blog contains step by step to get the certificate.
See discussions on LowEndTalk especially this comment to properly chain the certs together to be recognised by modern web browsers.
A free chinese SSL certificate should be ringing your alert bells.
Obviously consider your customers first when signing up to this.