Sourcegraph provides IDE-like tools for GitHub to make code search, browsing and navigating code more delightful. Get multi-repo search, jump to definition, find references, and file tree navigation.
I find this extension really helpful when exploring unfamiliar code.
Pros:Provides editor like functionality while browsing code on GitHub. Gives you context around GitHub code you wouldn't otherwise have.
Cons:Does not support all languages. Only supports Go, TypeScript, Python, and Java.