Varnish is one of my favorite pieces of technology. It’s a reverse caching proxy that makes slow websites go fast. It comes with some useful binaries to measure and monitor a running instance.
Varnishstat is one of those binaries: it lists
I like ElasticSearch, it’s a great piece of open source technology. Although it was built as a Lucene based search engine, it can do more than just that. It’s an awesome analytics engine, but it’s also a pretty good NoSQL database.