Great stuff. I was hoping somebody would integrate source code cross referencing with Git. Hopefully Github will integrate your tool with all their repos and it will be seamless for end users.
We believe developers deserve to have a hackable, extensible platform for their code, so it can be more deeply integrated with the best other dev tools. That's why we built Sourcegraph and released Sourcegraph's source code. It's also why we're making it easy to build deep integrations into Sourcegraph (see, e.g., https://src.sourcegraph.com/sourcegraph@master/.tree/platfor...).