CloudFlare - Cloudflare is a global network designed to make everything you connect to the Internet secure, private, fast, and reliable.
NakedSSL - Hassle-free SSL clothes for your naked domains.
Google Project Shield - Google's DDoS protection service
SSL Alerts - Free service to send SSL certificate expiration alerts
BrandSSL - On demand SSL for SaaS
Qloaked - Painless customer SSL for SaaS businesses