Google Publisher Tag (GPT) is an ad tagging library for Google Ad Manager which is used to dynamically build ad requests.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Sirdata is a self-service, third party data-collecting platform that specialises in the collection of behavioural data, predictive targeting and selling of audience segments.
Varnish is a reverse caching proxy.