One thing I wish GitHub made easier is responding to a pull request with a patch rather than encouraging reviewers to type up a bunch of suggestions that the original submitter will have to turn into a patch themselves.

If you have a better idea how to accomplish part of a suggested change, you can communicate that more clearly by making a patch and leaving a comment explaining why. GitHub should encourage this and allow the submitter some interface to easily incorporate that patch into his PR.

This is especially useful in situations where the only changes are in documentation or writing rather than code. Dealing with a dozen responses of "s/topy/typo/" should be as simple as clicking a few buttons to accept all the corrections. It would be less work for both sides.