The github-issues.vim (GitHub: jaxbot / github-issues.vim, License: MIT) by Jonathan Warner allows you to look up GitHub issues using Vim. That means the next time you're writing a commit and want to reference a ticket, you can get completion based on issue numbers.
:Gissues will show the issues for the current repository. If you want to use it with private repositories, then you'll need to set your API access token using
let g:github_access_token. Tokens can be obtained from /settings/tokens/new on GitHub.
:Gissues, you should be able to press return on an issue to view it as plain text. The output opens in a split window. Because GitHub issues works well with email, then the text view is perfectly acceptable.
The project has been around for a few months now and it looks like it's shaping up nicely. It's built with Python, and should work with minimal configuration.