How about communities, forums, boards? When I see an interesting project I'd like to talk to the developer without cluttering the Issues section.
It could be the entry point of every repo, moderated by the owner of course (something like php docs where people can post interesting stuff related to the page at the end). And it would make Github more social.
Why do you think you'd be cluttering the issues section? I wouldn't let that (your) perception stop you. Just open the issue if you have something to say.
Please don't. Issues are for bug reports and are not a support forum. If the repo maintainer asks in the README that usage questions should first be asked on Gitter, Slack, or Stack Overflow, please respect that request!
Feature requests are fine, since, like bugs, they have a defined scope and will eventually be done. However, I've seen some major products move their feature requests to a platform like UserVoice that's designed to track votes and progress.
That's why I wish every project had an IRC channel or something - it's a PITA trying to contact a maintainer or project creator because they don't always include their email and github doesn't have private messages.
I think a dev-social site like that should be separate to GitHub and just use their API to pull in repo data.
Someone should probably give a go at making a site like that. Making it easier for project owners to find contributors and for potential contributors to find projects. Facilitating discussions beyond in issues, etc.
It could be the entry point of every repo, moderated by the owner of course (something like php docs where people can post interesting stuff related to the page at the end). And it would make Github more social.