Recently one of the largest mobile providers in the UK (O2) had a bunch of downtime because of an expired SSL certificate. This free tool monitors your domain and sends an email when a certificate is going to expire so you can avoid that for your sites.
Kind of ironic that this site doesn't have an SSL cert
It seems like this site is down... so perhaps I can pitch my alternative, https://watchmyssl.com, which I just launched.
Feedback is welcome!
very nice tool :)
Also available in https://www.indiehackers.com/product/webmaster-sidekick and strangely enough think that feature launched a few days before O2's outage.