Self built pc (E8400, 8GB, 128GB SSD) which I will upgrade in the next year or so. Two 24" monitors, thinking about upgrading to two 27".

Windows host, running VirtualBox images with Linux Mint. I run several images, each major project in a separate VM.

Almost 100% Clojure development.

SVC: Git mainly.

Editor: Eclipse + Counterclockwise.

For services, I use mostly Heroku and Github.

The best improvement I had in the last years was to buy a corner desk (such as this http://www.ikea.com/us/en/catalog/products/60251335/ ) instead of a regular desk. It's miles ahead in comfort.